Fuel injector question

[-=Jeff=-]

Okay.. would a LT5 run like complete crap and load up on fuel with one leaky injector? or is there some other issue?

I do know, swapping injectors (all 16) fixes it and I do know one of the ones removed leaks (drivers side injector closest to firewall)

the set with the leaker is newer, I have gotten a replacement for the leaker and want to swap out my Multecs, but I want to see if that one would have been causing my issues for loading up..

Also that one injector was a steady drip, drip, drip with key on

Thanks

[secondchance]

Could you explain "loading up"?
Do you mean the car feeling as if it's choking?

My 94 was running fine when in open loop but as soon as she went into open loop she would ping at light load part throttle.

I replaced all 16 and in retrospect, even when cold,Iwas not quite getting all 405.

Although I did not test old multecs (threw them out vengefully!), my theory was one was leaking (excess fuel). When cold, a little excess would be tolerated but once warmed up, O2 sensor would read excess and trim back resulting in the rest of 3 cylinders running lean, back to normal, rich mixture... and so on.

[tccrab]

I can't speak for leaky injectors, but I had two primary injectors fail and my Z ran like sh!t.
My guess would be that anything that causes the air/fuel ratio to significantly differ from the optimal 14.7 : 1 will cause problems.

TomC
"Crabs"

[-=Jeff=-]

Originally Posted by secondchance

Could you explain "loading up"?
Do you mean the car feeling as if it's choking?

My 94 was running fine when in open loop but as soon as she went into open loop she would ping at light load part throttle.

I replaced all 16 and in retrospect, even when cold,Iwas not quite getting all 405.

Although I did not test old multecs (threw them out vengefully!), my theory was one was leaking (excess fuel). When cold, a little excess would be tolerated but once warmed up, O2 sensor would read excess and trim back resulting in the rest of 3 cylinders running lean, back to normal, rich mixture... and so on.

Loading up on fuel.. too much fuel, but then the one bank would show lean and then it would adjust to go rich but then see too much fuel on the other bank from the leaker. but that just does not make sense

[secondchance]

I suspect mine was doing the same thing. Perhaps not as severe.
When hoked to Tech 1, I was told by the mechanic that one bank (I guess 1-3-5-7 and 2-4-6-8 are processed separately by one O2 sensor each), passenger side, O2 reading was fluctuating.

It wasn't too bad untill about 2 months ago when it got real bad. I suspect initially one injector was probably leaking and then finally it died. I did not bother to check injectors after removal so I don't know this for sure.

As you know, after replacing w/ FIC injectors she has been running flawless.

To answer with your question, based on my experience, one leaker was making mine run like crap. Especially when in closed loop.

Good luck!

[-=Jeff=-]

Originally Posted by secondchance

I suspect mine was doing the same thing. Perhaps not as severe.
When hoked to Tech 1, I was told by the mechanic that one bank (I guess 1-3-5-7 and 2-4-6-8 are processed separately by one O2 sensor each), passenger side, O2 reading was fluctuating.

It wasn't too bad untill about 2 months ago when it got real bad. I suspect initially one injector was probably leaking and then finally it died. I did not bother to check injectors after removal so I don't know this for sure.

As you know, after replacing w/ FIC injectors she has been running flawless.

To answer with your question, based on my experience, one leaker was making mine run like crap. Especially when in closed loop.

Good luck!

you have a 94 and are running FIC injectors with no issues?

I have FIC injectors ( new ones) the leaker has been replaced but I have been hesitant to reinstall them.. the force it takes to install the new ones is less then the old ones

[secondchance]

you have a 94 and are running FIC injectors with no issues?

Yes.

I have FIC injectors ( new ones) the leaker has been replaced but I have been hesitant to reinstall them.. the force it takes to install the new ones is less then the old ones

Based on my experience, pulling old one were tough (probably due to years and stiffend O rings).

New ones, after being greased with Vaseline, were easier to slip into rail as well as into IH.

Did you make sure you got the right set talking to Jon?

[-=Jeff=-]

Originally Posted by secondchance

you have a 94 and are running FIC injectors with no issues?

Yes.

I have FIC injectors ( new ones) the leaker has been replaced but I have been hesitant to reinstall them.. the force it takes to install the new ones is less then the old ones

Based on my experience, pulling old one were tough (probably due to years and stiffend O rings).

New ones, after being greased with Vaseline, were easier to slip into rail as well as into IH.

Did you make sure you got the right set talking to Jon?

Yes.. I bought FIC last year.. had issues (kept running rich), sent them back, he sent another set, but I ran my old with Multecs all year to verify car was good with no issues.

Went to install the FICs in Feb/March, Jon asked to send them in to be checked (these were never opened from Package). Sent them back, he sent another set.

Installed the new set in the car, idled fine.. as soon as I drove (within the first 1/4) it was stumbling and loading with fuel..

I have over 100 emails of Jon and I back and forth, what to try check etc.

I got some bits from him the other day and last night found that the pieces I already had were the correct ones.

I know guys running FIC injector with no issues.. you are the 1st one i have heard of with later IH running them. I also have Later IH (93-95) in my 90. The FIC injectors are going in the same distance as the Multecs. they go in a bit easier then the multecs, which makes me think it is vacuum leak on the injector. I have a couple things I need to check on my injectors ( the FIC) ones when I get home, but I am at a loss as to the problem. unless it was that one injector causing issues.

not sure what to do, I need another set of Gaskets for a plenum pull as I am not sure mine will last much more.. but the car runs fine with Multecs for now.. I really wish I knew the exact problem

I mean I can tell it is getting rich, but if there is a leaker it should go lean.. and not get loaded with fuel.

[secondchance]

It's a tough one.
I think 90 thru 92 had 2 different lbs for primary and secondary. Are you running 21 lbs injectors for both?

If I remember correct, 90-92 had smaller flow rate for primary and higher flow rate relative to 93-95.

Is it possible your primary injectors may have higher then original resulting in flow too high even for ECM to control?

I am trying to get hold of 90-92 owner who may know what flow rate injectors came from the factory.

Anyone out there know this info?

If I get the answer I will post ASAP.

[-=Jeff=-]

Originally Posted by secondchance

It's a tough one.
I think 90 thru 92 had 2 different lbs for primary and secondary. Are you running 21 lbs injectors for both?

If I remember correct, 90-92 had smaller flow rate for primary and higher flow rate relative to 93-95.

Is it possible your primary injectors may have higher then original resulting in flow too high even for ECM to control?

I am trying to get hold of 90-92 owner who may know what flow rate injectors came from the factory.

Anyone out there know this info?

If I get the answer I will post ASAP.

possible yes to the different rates as I don't know either, but right now I am running 16 secondary OEM injectors with no issue, so I don't think that is it.