Misfire after new injectors installed

[Hot Air Beast]

I am starting a new thread simply because the information is now buried on the second page of an old thread and may not be seen by very many people.


Engine misfire after dealer installs new injectors - 1984 GN

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OK so here i am again, hat in hand and praying for help!

I had an extreme rough idle and yet car still performed well at WOT- took 84 GN to a respected GM dealer in a town close to Ottawa, Canada, with a shop foreman who has a great reputation (built a very cool rat rod).

Car diagnosed with a need to replace 29 year old injectors and 29 year old IAC motor.

OK that done and now the car has a misfire (I believe). Idle is better. Car sounds like it is running on four or five cylinders and car shakes from 0-130 kph. If you drive gently the shake/shudder/misfire is most prominent around 75kph when she drops down into overdrive and labours when getting up to speed.
Dealership seems to be at a loss to figure this out and I am frankly getting very discouraged. Car is back in my hands for two weeks before it goes back to the dealer.

Your thoughts and suggestion will be most appreciated.

__________________
Phil's 84
Owned since 1988
Bone stock and OK with that!

 

[TurboBuRick]

Got to love modern day dealer tech's.

Well, I would start by reading the spark plugs. See if they all look the same or??

A infra red heat gun can help. Cylinders that miss will be colder the rest. Check the pipes. Once it's determined what cylinders are missing, you can move onto why? Could be spark drop out, could be flooding out, Could be leaning out.

I would double check the plugs on the injectors. The firing order as well. Inspect the harness for burnt wires.

Rick

 

[Hot Air Beast]

Duh!!!!!!!!
Plugs on the injectors it is. The plastic connector was broken on #1 and metal wire didn't hold well on the injector itself. Tie wrap for now - problem solved. Wouldn't you think the dealership that installed the injectors would have done that the second time i brought the car in to them!!??

Much thanks to everyone who made suggestions. Oh well - got to test coils, spark plugs, wires, vaccum lines etc - all good to go.

Now i can get back to driving - yea!!