350 TBI Engine Miss

[JC_32]

I am having an issue with my 1987 Chevy R-10 with a 5.7 TBI and a 700R4 Transmission.

Symptoms: Noticing a light and hard miss at idol while in gear.

details: This only happens while in gear and if the motor is warm
If motor is warm and I take it out of gear there is no miss.
No miss while driving at any speed.
Still getting 17-18 MPG

Recent Work: Complete tune-up.
Changed plugs, cap, rotor, wires and timing.
timed to 2 degress BTDC with the plug disconnected.
disconnected ground then reconnected so computer would set advance curves.
New O2 sensor and Cat.

Clarifications: When I gapped the plugs, the mfg recommended .35 but my book said .45
I gapped at .35 (should I go to .45?)
The truck does burn some oil.


I look forward to hearing some input.

thanks,

[irishman999]

It sounds like a plug wire is not making contact.

[GmtGmt]

Originally Posted by irishman999

It sounds like a plug wire is not making contact.

X2

did it start to miss after the tune up?
i would try see if the plug wires can be push farther down over the plug some times the wire can be at the end of the rubber boot so its just bearly making contact if that dosent work i would try another set of plug wires to see if it changes anything my diffrent make

[JC_32]

After the tune-up it ran great!!
a few tanks of gas I was getting almost 19mpg which is pretty good.

It's been progressively getting worse.
I haven't had time to look at it yet, but thought I would throw the post up to see if there were some suggestions other than what is on my mind.

my thought is the plug gap mixed with the oil burning. I'm thinking it's causing a plug to "clog" up due to the size gap?



thanks for the replies.

[irishman999]

if you are sure the plug wires are making good contact pull your plugs and gap them the extra .10, clean them off with a wire brush too. where did you buy the plug wires and tune up parts?

[spudz]

Sounds like a cracked plug or cheap parts store wires.

[JC_32]

The plugs are AC Delco and the tune-up parts picked up at O'Reilly's.
(putting up my shield to protect against the lashing..lol)

[JC_32]

deleted...duplicate post???

[irishman999]

No big deal and no lashing, i did the same dumb move. The distributor cap i got from orielys melted the button that the rotor made contact with. Take all that bs back to orileys and try to get your money back, then go to Autozone and buy the premium components.

[JC_32]

Spudz, what wires do you recommend?

[spudz]

ac delco, taylor, moroso, msd, ect.. Nothing from a parts store.

[JC_32]

All tune up parts are BWD with AC Delco plugs.
Posted via Mobile Device

[nbpro]

Originally Posted by spudz

ac delco, taylor, moroso, msd, ect.. Nothing from a parts store.

taylor all the way