Tbi swap build thread

[brontotx]

Originally Posted by rfmaster

Turn ignition key into RUN position (do not crank). With a DVM measure voltage (with respect to engine ground) on both injector terminals - you should have voltage (11.5 to about 12Vdc) on both sides of the connector. Repeat for for both connectors.

When you pour a bit of gas into TB do you get engine firing up???

//RF

Sorry, RF, but I respectfully disagree. Again, I'm no expert (I'm worse - I'm an engineer), but my understanding is that one side of each injector always has the 12V+ and the ground is switched/pulsed to the other terminal/side of the connectors by the ECM. Thus, testing for voltage across both injector connector terminals as you suggested will not show 12V (I just checked my truck and confirmed the lack of 12V across the injector connector terminals when in RUN).

With the key in RUN position, you should be able to measure 12V from the red wire on one connector (or the white wire on the other connector) to an engine or chassis ground, but not to the other connector terminal.

In regard to pouring gas into the TB, he said it would start in post #186.

cjracing: The relationship between the ignition module in the dizzy and the injectors is that the module tells the ECM that the engine is spinning (and at what RPM). The ECM needs to check that the engine is spinning because it is a potentially very dangerous situation if the ECM allows the injectors to fire (i.e.,release fuel into the TB) when the key is in the RUN or START positions and the engine isn't spinning. Since FB72 said his engine would start when he poured gas into the TB, the ignition module is working fine and it is my belief that his problem is (1) an ECM problem, (2) an open in the wiring between the ECM and the injector connector, or (3) a stuck/defective injector.

Since the injectors are basically solenoids, I reiterate my earlier suggestion to apply a ground to the non-12V+ terminal of the connector to see if the injector will fire. With a confirmed 12V+ on one injector terminal and a ground to the engine or chassis on the other, the solenoid/injector should click and allow fuel to flow. If fuel doesn't flow, either (1) the injector is stuck or defective or (2) there is no fuel pressure in the injector pod. If fuel does flow, then the problem is upstream of the injector connector in the ECM or wiring. While I've never tried this test, I don't see why it wouldn't work, nor do I think it risks harming anything.

That is my $0.02 and please understand that I am not trying to offend anyone or debate their advice - I'm simply trying to help.

Mark

[rfmaster]

Originally Posted by brontotx

Sorry, RF, but I respectfully disagree. Again, I'm no expert (I'm worse - I'm an engineer), but my understanding is that one side of each injector always has the 12V+ and the ground is switched/pulsed to the other terminal/side of the connectors by the ECM. Thus, testing for voltage across both injector connector terminals as you suggested will not show 12V (I just checked my truck and confirmed the lack of 12V across the injector connector terminals when in RUN).

With the key in RUN position, you should be able to measure 12V from the red wire on one connector (or the white wire on the other connector) to an engine or chassis ground, but not to the other connector terminal.

That's what I said. Kindly re-read my post (engine is not turning).

Furthermore, measuring voltage drop across 1.1 Ohm injector with a common DVM is fruitless. However, with a dual trace O-scope and A-B function one can measure voltage drop across operating injector. But that's not an issue here. In TBI system (same technique is used in many other injector systems as well) one pin of injector is tied +12 volt bus, while the second pin is being tied to a switching circuit inside ECM. Typically this switch circuit consists of high power Bipolar or FET transistor. In case of 1227747 ECM GM used a high power NPN transistor with collector tied to floating injector pin, while emitter is shunted to ground with 0.1 Ohm resistor. A custom (Delco) injector transistor driver IC is used to current limit current drawn by injector - by monitoring voltage drop across 0.1 Ohm shunt.

Originally Posted by brontotx

In regard to pouring gas into the TB, he said it would start in post #186.

Missed that one, sorry.

Originally Posted by brontotx

cjracing: The relationship between the ignition module in the dizzy and the injectors is that the module tells the ECM that the engine is spinning (and at what RPM). The ECM needs to check that the engine is spinning because it is a potentially very dangerous situation if the ECM allows the injectors to fire (i.e.,release fuel into the TB) when the key is in the RUN or START positions and the engine isn't spinning. Since FB72 said his engine would start when he poured gas into the TB, the ignition module is working fine and it is my belief that his problem is (1) an ECM problem, (2) an open in the wiring between the ECM and the injector connector, or (3) a stuck/defective injector.

Since the injectors are basically solenoids, I reiterate my earlier suggestion to apply a ground to the non-12V+ terminal of the connector to see if the injector will fire. With a confirmed 12V+ on one injector terminal and a ground to the engine or chassis on the other, the solenoid/injector should click and allow fuel to flow. If fuel doesn't flow, either (1) the injector is stuck or defective or (2) there is no fuel pressure in the injector pod. If fuel does flow, then the problem is upstream of the injector connector in the ECM or wiring. While I've never tried this test, I don't see why it wouldn't work, nor do I think it risks harming anything.

That is my $0.02 and please understand that I am not trying to offend anyone or debate their advice - I'm simply trying to help.

Mark

OK = 2 cents accepted (in this economy)
//RF

[cjracing15]

cjracing: The relationship between the ignition module in the dizzy and the injectors is that the module tells the ECM that the engine is spinning (and at what RPM). The ECM needs to check that the engine is spinning because it is a potentially very dangerous situation if the ECM allows the injectors to fire (i.e.,release fuel into the TB) when the key is in the RUN or START positions and the engine isn't spinning. Since FB72 said his engine would start when he poured gas into the TB, the ignition module is working fine and it is my belief that his problem is (1) an ECM problem, (2) an open in the wiring between the ECM and the injector connector, or (3) a stuck/defective injector.

Ok the way I understand how the cranking sequence works is the cpu gets a signal from the starter (C-9 prpl wire that goes to the selinoid on the starter)to turn on the fuel pump while it is cranking. When the engine has oil pressure the oilpress switch is what tells the cpu to run the pump and I understood that the module is what fired the injectors in time with the engine while it is running.
Am I wrong? If I am I would like the right sequence.

By the way FB-72 you have checked to see that you have 12 volts to the pump right? If you have and I missed it I am sorry I am just trying to help ya out.

[FRENCHBLUE72]

I do have power to one side of the injector while cranking but the other side does not flash?? (for some reason I cannot edit my posts)

[brontotx]

With ignition on, you should have 12V+ on both the red and white wires. The injectors do need a solid 12V, so if your battery is weak, they may not fire. The blue and green wires are triggered by the ECM to ground for firing each injector. There are ways to check the injector pulses at the wiring connectors, but require specialized equipment like an oscilloscope or trigger lights.

It is possible the injectors are stuck from having gummed up sitting around -this is what the problem was with mine when I first tried to start it and I was able to get one un-stuck by rapping the injector pod on the side with the handle of a large screwdriver. If you can get one to spray (the truck will run rough on just one injector), a good way to see if they are operational is to use a strobe from a timing gun. I ended up having to buy a new injector for one side.

I doubt that excessive fuel pressure is the problem - I'm pretty sure the bypass regulator is after the point where fuel is pressurized to the injectors. While I'm not sure what harm could be done since I've never tried this, you could try to momentarily connect a ground to the terminal of the injector that doesn't have 12V+ to see if it sprays (to try this, you have to have fuel pressure at the injector). If it sprays, there is either an ECM or wiring problem between teh ECM and the injector, otherwise it is probably the stuck injector I mentioned above.

BTW, I'm no expert on this, I've just been down this road before and I'm trying to give you the benefit of what little I know. Hope this helps and good luck.

Mark

[FRENCHBLUE72]

I lightly rapped on the injectors and nothing sooooo I guess I ll wait for a few others to chime in...

[brontotx]

While I get the sense that you want to figure this out quickly, these "noid" lights are the cheapest way (available on e-bay for $5-10) to see if all the wires at the injectors are getting the correct signal (i.e., determine if the lack of spray is due to the ECM/wiring or the injectors). Perhaps they are available at your local auto parts store.

BTW, I had to rap on my injectors pretty solidly before the one started spraying.

Good luck,

Mark

[cjracing15]

Originally Posted by FRENCHBLUE72

I lightly rapped on the injectors and nothing sooooo I guess I ll wait for a few others to chime in...

Do you here your injectors clicking while you are cranking the motor? If you do they have the right voltage to fire them because that is the clicking noise. If they are clicking that probably means not enuff fuel is getting to the injectors.
I had this same problem and it ended up being a pinched fuel line.

I think the injectors get there signal from the ignition moduel in the distributor. If it is bad you might have spark but the injectors will not fire or vise versa.

keep us posted and good luck,
Jamie

[FRENCHBLUE72]

The batt in my voltage meter has decided not to play today so I quickly probed the wires and I have at least some power to one side of the injector connection on both sides injectors the other wire does not have any voltage(at least not that the test light shows) with the key in any position or while cranking the engine... Looks like i'm off to town for a battery for the meter.. Again guys thanks so much for the many good points of view..


Also on a side note I have a friend bringing over his scanner for the diagnostic port will this tell me anything ???

[rfmaster]

Originally Posted by FRENCHBLUE72

The batt in my voltage meter has decided not to play today so I quickly probed the wires and I have at least some power to one side of the injector connection on both sides injectors the other wire does not have any voltage(at least not that the test light shows) with the key in any position or while cranking the engine... Looks like i'm off to town for a battery for the meter.. Again guys thanks so much for the many good points of view..


Also on a side note I have a friend bringing over his scanner for the diagnostic port will this tell me anything ???

I'll put together a basic measurement diagram later tonight - this should help you to troubleshoot. I hate guessing and once you have check list it will make it simpler to troubleshoot further.

Scanner
The ALDL will not tell you why injectors are not firing. On the other hand 7747 ECM will give you sensor data. Injector functionality is not monitored by early ECM - we are talking '80 high tech here (PC-AT, remember those 8086??)

//RF

[glock35ipsc]

rfmaster - those diagrams you post up are great, and a bunch of help for someone who hasn't looked at a TBI since the early 90's! I take it you are making them?

[cjracing15]

Originally Posted by glock35ipsc

rfmaster - those diagrams you post up are great, and a bunch of help for someone who hasn't looked at a TBI since the early 90's! I take it you are making them?

Yhea Thanks RF for your work on those diagrams they are awsome.

[FRENCHBLUE72]

Cj if your talking about the fuel pump no I have not checked but the return line is filling up the 5 gallon can quickly... I have 12 volts dc to both injectors on one side only...

[cjracing15]

...

[pancake]

Hello again, I have a quick question.

If I use a adapter plate to bolt the TBI to a carb intake:

1) are there rules on whereto mount the sensors that were mounted to the TBI intake.

2) can I use a diffrent coil mounted to the firewall? what kind of coil do I need?

Thanks again.

[cjracing15]

Originally Posted by pancake

Hello again, I have a quick question.

If I use a adapter plate to bolt the TBI to a carb intake:

1) are there rules on whereto mount the sensors that were mounted to the TBI intake.

2) can I use a diffrent coil mounted to the firewall? what kind of coil do I need?

Thanks again.

1) I would put the sensors as close as I could as the factory did it.

2) As for the coil I am not sure. I am sure RF will chime in on it. He rocks on the wiring diagrams.

[rfmaster]

Originally Posted by cjracing15

1) I would put the sensors as close as I could as the factory did it.

2) As for the coil I am not sure. I am sure RF will chime in on it. He rocks on the wiring diagrams.

Thanks CJ

Pancake - you can mount coil on the fire wall (or in its original location). If you do so make sure to run a ground strap (braid) between intake and coil mounting bracket. Low resistance ground return path is required between EST and coil.

I have seen third gen boys mount monster sized coils (lots money) on the firewall. Generally, performance coils can be saver and trouble all rolled into one. The problem stems from current requirement that these coils place on EST module (inside dizzy). To get HV coil to deliver joules of spark energy (at 40 - 50kV) requires more current flowing through the primary (12 volt winding). EST module operates as a switch which turns on & off current flowing through the coils primary windings. More current = more heat. Semiconductor devices do not like heat and fail over time if subjected to operation beyond rated limits. For our trucks, with engines spending most of their lives below 3000 RPMs use of 'monster' coils is not necessary.

One of these days I'll setup experiment in my lab to measure primary coil winding current and publish my results. I have factory coils, but I do not have any 'monsters' for obvious reasons.

As to recommendation on coil - I have never used anything but stock, hence I can not recommend one.

Sensor placement. I prefer to mount my sensors away from heat sources for the aforementioned reasons. I mounted my MAP on the firewall, ESC module is mounted on fender skirt. All my relays are mounted away from engine. GM mounted the same sensors on a bracket bolted to intake manifold.

//RF

[pancake]

rfmaster, find anything good at the swap meet?

68TT, i know Earls sells the metric to -6AN fittings to attach an AN fitting to the TBI supply and return...I will try to get part # if you need it.

I have still not received/installed a fuel pressure gauge but I did a little more troble shooting..

I think that the Intake manifold is leaking on the passenger side center by the EGR. I took a can of carb cleaner and sprayed around the intake and it showed a noticible difference. The engine almost died. Would this indicate a vacuume leak? Can the egr "suck" up carb cleaner? It also seemed to be leaking on the driver side towards the back.

I beleive that my "machining" of the center bolt holes did not go so well.

The intake I orginally took off does not have an EGR so I think I will have to get another intake.

I was looking at the Edelbrock Performer intake manifold 3701. I would have to get an adapter plate, but it does have an EGR.

I was also looking at Arizona TPI...I belive they sell stock TBI manifolds that they actually machine....probably did a better job than me

Do you guys have any sugestions?

Is the 3701 intake to "radical" for the TBI?

I was thinking about re-mounting the TBI intake that I "machined" but I dont think it will work. Don't want to wasted my liminted time.

Again, thanks for the help, support, and knowledge you guys are sharring

[rfmaster]

Hey pancake

Earl's 991955 Blue Anodized Aluminum -6AN Male to 16mm by 1.5 Power Steering/ Fuel Injection Adapter Fitting. These are pricey if you ask me (nice quality non the less). A lower cost alternative is from Russell Performance 648060 - Russell AN to Metric Adapter Fittings -6 AN to 16mm x 1.5 Male for supply rail ($8) and Russell Performance 648070 - Russell AN to Metric Adapter Fittings -6AN to 14mm x 1.5 O-Ring for about 11$

Summit also offers their own brand (probably made by Accel ) Fuel Rail Fittings, Aluminum, Blue, TPI, One -6 AN to 16mm x 1.5 O-ring, One -6 AN to 14mm x 1.5 O-ring, SUM-220009 for about $20.

Pomona swap meet is great, but it is huge. It takes about 3 hours just to walk swap meet - cars for sale that's another story all together. I was not looking for anything in particular, but if a clean hood, right fender and door presented itself (for a right price) I would have made my move. But, as luck would have it I did not see any, besides the '90 323 makes for poor transportation means for a hood! Did manage to get a good deal for truck cover and a pair of NIB Maglite flashlights and some Snap-On sockets. The thing to remember about swaps meets that there is always next month.

I am trying to convince my XYL that I need (haha) a new project, but that's another story all together.

Intake manifold leaks and modified bolt holes - there is only one solution that I can offer you in this regard. Get intake manifold that matches your head's intake bolt pattern. In 1986 GM made several changes to Gen 1 SBC - one being altering intake manifold angle from traditional 90 deg to 70 deg. Elongating holes, inserts shortly followed. IMHO it is a false economy approach.
Leaks occur partly due to unequal distribution of clamping force.

For 1986 and earlier heads 3701 is a good choice if you plan to run Carb or TB with adapter. 3701 is a good choice for a stock or slightly modified engines. It is a dual plane, non air gap design. TBI works best with dual plane heated intake manifolds (i.e 3701).
I run Holley 300-49 TBI specific intake - with block off EGR. There are no leaks thanks to a quality gasket between block off plate and manifold. The only problem with Holley intake is that there is limited clearance for fuel lines! I had to use 1" TB spacer to raise TB above intake flange to get enough clearance for fuel lines. So be careful with type of adapter (TB to Q-jet) you are going to get - get the one that offers fuel line clearance (rear or center mounted TB)!

//RF

[68 TT]

Originally Posted by rfmaster

Hey pancake

Earl's 991955 Blue Anodized Aluminum -6AN Male to 16mm by 1.5 Power Steering/ Fuel Injection Adapter Fitting. These are pricey if you ask me (nice quality non the less). A lower cost alternative is from Russell Performance 648060 - Russell AN to Metric Adapter Fittings -6 AN to 16mm x 1.5 Male for supply rail ($8) and Russell Performance 648070 - Russell AN to Metric Adapter Fittings -6AN to 14mm x 1.5 O-Ring for about 11$

Summit also offers their own brand (probably made by Accel ) Fuel Rail Fittings, Aluminum, Blue, TPI, One -6 AN to 16mm x 1.5 O-ring, One -6 AN to 14mm x 1.5 O-ring, SUM-220009 for about $20.

I'm too cheap even for that

I like the $1 each cad plated steel pipe to AN fittings I get from the local hydraulic shop.

I had the hydraulic shop solder on some -06 male fittings onto the metal fuel lines that came off the regulator and the metal lines coming off the fuel tank sending unit. It made plumbing to them much easier and only cost about $5 each installed.

[pancake]

Hi Guys,

After thinking about my intake manifold leaks I decided to by a Edelbrock Manifold #3701, a TBI adapter plate #2296, and some new fuel fittings.

I also ordered a new distruibtor because my old one had cracked wires inside and it needed a cap and rotor...was eaiser for me to order a new one then mess with fixing the wiring.

Oh....and a fuel pressure gauge

The parts should be here Friday and I will have it installed this weekend. I will keep you updated on the progress and will post before and after pictures when I am finished.

Thanks again for the help, Pancake.

[pancake]

Hello again guys,

Well I received the parts today (intake) and I found that my stock EGR will not bolt-up to the intake....I called Summit and they do not offer anything to adapt my EGR to the intake. It seems like one issue after another. I knew that it would not be very easy, but I did not expect to run into this many problems!!

Do you people have any suggestions?

Can I eliminate the EGR? This would be the simplest thing to do, and then I could use my old intake and save $165.

Do I need the EGR? Will I have to get a new chip if I eliminate it?

I was so close to getting it going!!

Any suggestions would be greatly appreciated...Thanks again

[68 TT]

Originally Posted by pancake

Hello again guys,

Well I received the parts today (intake) and I found that my stock EGR will not bolt-up to the intake....I called Summit and they do not offer anything to adapt my EGR to the intake. It seems like one issue after another. I knew that it would not be very easy, but I did not expect to run into this many problems!!

Do you people have any suggestions?

Can I eliminate the EGR? This would be the simplest thing to do, and then I could use my old intake and save $165.

Do I need the EGR? Will I have to get a new chip if I eliminate it?

I was so close to getting it going!!

Any suggestions would be greatly appreciated...Thanks again

Eliminating EGR seems simple but has some pretty big repercussions in the tune. It effects timing and fuel economy. There is a pretty in depth discussion about this on thirdgen.org

You can do without it but I wouldn't if at all possible. Maybe you can find a different vintage one to install that will fit the intake.

A mail order tune will have a hard time correcting for the missing EGR. Every engine will react differently to timing changes due to the vehicle package it is pulling around.

You can get all the stuff needed to burn your own chips and data log your running engine for under $150. Check out the DIY PROM section at thridgen. It's not that hard to make minor changes and it is really nice to be able to data log what is going on in your engine too.

[68 TT]

Originally Posted by pancake

Hello again guys,

Well I received the parts today (intake) and I found that my stock EGR will not bolt-up to the intake....I called Summit and they do not offer anything to adapt my EGR to the intake. It seems like one issue after another. I knew that it would not be very easy, but I did not expect to run into this many problems!!

Do you people have any suggestions?

I say call the Edelbrock tech line and ask them what application EGR valve the intake was designed to use. The gasket looks like the late 70's & early 80's vintage car ones I have seen.

[pancake]

I was looking around Rockauto and found several EGR valves. I have no idea which on will work.

I was looking for a 1983 EGR valve and came up with several options...

Does anyone know which one will work for my application? (350ci 4x4 and it will have a full manual valve body automatic tranny, no emission requirments, only a trail rig, will not be driven on the road)

Will this work ? DELPHI Part # EG10074 OE No 17113439, 17084818
or ACDELCO Part # 2141441 (high altitude)


What is the difference between all these EGR valves?

Do I need a high altitude EGR living in Colorado and driving the 4x4 at high altitude (over 10,000 feet)?

I have no problem using the new intake manifold if I can find an EGR valve that will fit it and work for me.

Thanks again, Pancake

This is what the EGR valve gasket that came with the new intake looks like..I need to get a EGR to match this base.