symptoms of stuck injectors??

A

at7we2

Member
Joined
Oct 31, 2003
I let my GN sit in the garage for approx. 6 weeks (been really busy lately). :rolleyes: it was running perfectly when I parked it, but I started it up yesterday and it seemed like it was only running on 4 or 5 cylinders. :mad: plug wires and electrical connections checked out OK so I got out my old mechanic's stethescope and started probing around. probed around on the valve covers - valve train sounded fine, probed around on the header primaries and noticed #5 did not sound the same as #'s 1 and 3. moved on to probing the injectors - listened to all 6 injectors with the stethescope and #'s 1, 3, 4, and 6 were all making the usual "tick-tick-tick-tick" sound however #'s 5 and 2 were not "ticking". After that I noticed the exhaust did not smell the same as usual, I could be wrong, but it smelled like maybe it was running lean - it usually smells a little rich, but not yesterday. I didn't think to look at the O2 mV before I shut it down and went back inside (I was a little cranky at that point). Based on those symptoms, does it sound like I've got two stuck injectors?

Thanks for reading.

Rob
 
yes they should be ticking. all of mine do. could be harness, ecm or the injectors. need an injector pulse checker thingy that plugs into the harness to see if ur getting an injector pulse. if u are its probably the injectors.
 
boosted86 -

thanks for the reply.

Anyone have an injector pulse testor they'd loan me? :cool:
 
have not had an opportunity to look at this problem again, hopefully I'll have time this weekend. in the mean time, I've looked at some wiring diagrams and I noticed that the two injectors which don't seem to be working are #2 and #5 - these cylinders share an ignition coil on the coilpack. anyone have any idea *if* or *how* the fuel injectors are linked to the ignition coil? in other words is there anyway that a problem with the coil or ignition system could be affecting these two fuel injectors??? :confused: sounds strange to me, but I thought it was odd that:

1. I seem to have lost *two* injectors at the same time and
2. those two cylinders (#2 and #5) are on the same coil

I need to spend more time looking at the wiring diagrams, but that seems like a strange coincidence.
 
Also to make certain that those two cylinders are not firing, feel the exhaust header at the discharge of the cylinder (put a glove on first) . If temp is colder then the others, you will know for sure you are missing something for combustion (fuel, spark, compression).

As for losing two injectors, I would figure it’s an electrical problem. Possible wire or connection issue. But definitely a great tool to check will be the pulse tester.
 
finally back under the hood again...

ok, it's been two months since I discovered this problem and I'm just now having a chance to get back under the hood. :rolleyes: got laid off about a week after I discovered the problem so the Buick wasn't exactly a priority.

However, to put a positive spin on it, if my GN had been running *correctly* when I got laid off, I probably would have sold it in a panic. Fortunately I'm employed again and will hopefully stay that way for a while, so I'm back under the hood of my Buick this weekend.

Question: Is it ok to probe the injector pulse signal wires at the ECM connector with a standard test light or will that damage the injector driver module?

Thanks,
Rob
 
chevellejoe said:
feel the exhaust header at the discharge of the cylinder (put a glove on first) . If temp is colder then the others, you will know for sure you are missing something for combustion (fuel, spark, compression).
Click to expand...

Just run it for a few seconds, if its no lighting up and that header is cold, you found the cyl for sure. Then plug that wire into a spare spark plug and lay it on the inner fender to see if it sparks. I saw raw fuel pouring out my exhaust when I lost #2 fuel injector as stuck open.

If you have a stuck open injector, you'll need to change your oil as fuel is definitely in your oil.
 
TurboTnZ06 said:
Just run it for a few seconds, if its no lighting up and that header is cold, you found the cyl for sure. Then plug that wire into a spare spark plug and lay it on the inner fender to see if it sparks. I saw raw fuel pouring out my exhaust when I lost #2 fuel injector as stuck open.

If you have a stuck open injector, you'll need to change your oil as fuel is definitely in your oil.
Click to expand...

Thanks for the reply TurboTnZ06. I spent a little time on it this evening and, as is often the case when working on a turbo Buick, I've got more questions now than I did when I started chasing down this problem. Here's what I observed this evening....

  • checked each injector with a noid light at the injector plug
  • all 6 injectors are getting pulses based on the noid light
  • after disconnecting and reconnecting #2 injector plug, engine *seemed* to idle much better. That was one of the injectors I thought might not be cycling so I thought it might have had a little corrosion. After reconnecting it the idle really seemed to smooth out compared to what it had been, but still not quite right and didn't rev smoothly.
  • broke out the IR thermometer to check header primary temps.
  • very puzzled by the temp readings from the header primaries :confused:
  • #1 - approx. 430 deg.
  • #3 - approx. 360 deg.
  • #5 - approx. 240 deg.
  • #2 - approx. 230 deg.
  • #4 - approx. 350 deg.
  • #5 - approx. 440 deg.
so that's roughly a 200 deg. variation between the highest and lowest on each side and what was even more puzzling to me was the temps went high to low (front to back) on the driver's side and and low to high (front to back) on the pass. side :confused::confused:

now I realize that the IR thermometer may not be the most accurate way to get temp readings, but I got all the readings within 10 inches of the primary tubes.

As for getting spark, is it possible to check for spark from the CCCI with an induction timing light? I've got an old inductive timing light and that's one way I used to check points and HEI style ignition systems was just hook it on to each plug wire and make sure you were getting continuous spark pulses one plug wire at a time.

so, I've determed that I am at least geting injector pulses to all 6 injectors, still not sure they're all actually cycling though. I suppose one logical next step would be to pull the plugs, like Chuck Leeper suggested previously.

as always, any input is appreciated.

Thanks,
Rob
 
Give the injectors a love tap and see if car smooths out. If it does send them out and have them cleaned. dont trust them. You dont want them doing that at wot and 20psi:eek:
 
at7we2 said:
Thanks for the reply TurboTnZ06. I spent a little time on it this evening and, as is often the case when working on a turbo Buick, I've got more questions now than I did when I started chasing down this problem. Here's what I observed this evening....

  • checked each injector with a noid light at the injector plug
  • all 6 injectors are getting pulses based on the noid light
  • after disconnecting and reconnecting #2 injector plug, engine *seemed* to idle much better. That was one of the injectors I thought might not be cycling so I thought it might have had a little corrosion. After reconnecting it the idle really seemed to smooth out compared to what it had been, but still not quite right and didn't rev smoothly.
  • broke out the IR thermometer to check header primary temps.
  • very puzzled by the temp readings from the header primaries :confused:
  • #1 - approx. 430 deg.
  • #3 - approx. 360 deg.
  • #5 - approx. 240 deg.
  • #2 - approx. 230 deg.
  • #4 - approx. 350 deg.
  • #5 - approx. 440 deg.
so that's roughly a 200 deg. variation between the highest and lowest on each side and what was even more puzzling to me was the temps went high to low (front to back) on the driver's side and and low to high (front to back) on the pass. side :confused::confused:

now I realize that the IR thermometer may not be the most accurate way to get temp readings, but I got all the readings within 10 inches of the primary tubes.

As for getting spark, is it possible to check for spark from the CCCI with an induction timing light? I've got an old inductive timing light and that's one way I used to check points and HEI style ignition systems was just hook it on to each plug wire and make sure you were getting continuous spark pulses one plug wire at a time.

so, I've determed that I am at least geting injector pulses to all 6 injectors, still not sure they're all actually cycling though. I suppose one logical next step would be to pull the plugs, like Chuck Leeper suggested previously.

as always, any input is appreciated.

Thanks,
Rob
Click to expand...

:eek: hang on, I just re-read this thread from the top, including my own posts and I realized I may have answered my own question. in one of my previous posts, I commented that I *thought* it was inj's #2 and #5 that were not cycling and I noted that those cylinders share an ign. coil. more than one other member has suggested I look at spark as the problem, well, since the noid light showed all 6 getting pulses then it almost has to be spark! I was convinced it was the injectors because they didn't sound like they were ticking or ticking as loudly when I listened to them with a mechanics stethescope. still not sure why they sounded different. :confused: Anyway, after I posted the header temps, I realized they get colder toward #2 and #5 :eek: so that again points to those to cylinders has having problems, but since they are getting injector pulses *AND* share a coil, it must be an ignition issue. So NOW I know what to check tomorrow. :cool:
 
Injector prob

Had a similar problem with my car. I used a noid light to check for inj pulse and found no to weak pulse at #5 cylender. I did some snooping around alldata and found a old tsb on dirty contacts at the ecm .the grease they used retains dirt and gives you a poor contact at the harness. Once cleaned it was good as new.so start with a noid light(you can pick them up at autozone cheap)and take it from there....
 
chopped39 said:
Give the injectors a love tap and see if car smooths out. If it does send them out and have them cleaned. dont trust them. You dont want them doing that at wot and 20psi:eek:
Click to expand...

chopped39 - I posted my other replies before I saw yours. I'll try tapping the injectors first tomorrow since that's even easier than swapping out ignition components. If tapping the injectors doesn't help, I'll swap out the coil and if that doesn't work, I'll swap out the ign. module.

Thanks!
Rob
 
One more thing to check is to make sure you have 12 volts going to each injector harness plug.
 
Cam censor

Im new to the whole turbo buick hobby , but i am certified tech. Im not shure if the car is running right . Is it possible that the cam sensor is 180 off and will it run (poorly)? These cars beat to there own drum and im trying to keep the beat. Its a 84 converted to 87 w/ a 212/212 cam 30lb injectors power plate tt chip with a maf translator stock turbo alky system adjustable regulator . If any ideas please let me know... Thanks
 
at7we2 said:
chopped39 - I posted my other replies before I saw yours. I'll try tapping the injectors first tomorrow since that's even easier than swapping out ignition components. If tapping the injectors doesn't help, I'll swap out the coil and if that doesn't work, I'll swap out the ign. module.

Thanks!
Rob
Click to expand...

since you say the noid lights show there is signal to the injector you need to see if the injector is actually operating--------if you want to see if the injectors are working unplug them and connect a battery with test leads to them one at a time without the engine running in a quiet room--------when you make and break the connection you should hear a faint click-------if left to sit for a long time it is common for an injector to stick from rust or corrosion-------happens very often if there is any ethanol in the fuel..............RC
 
A2000RICH said:
since you say the noid lights show there is signal to the injector you need to see if the injector is actually operating--------if you want to see if the injectors are working unplug them and connect a battery with test leads to them one at a time without the engine running in a quiet room--------when you make and break the connection you should hear a faint click-------if left to sit for a long time it is common for an injector to stick from rust or corrosion-------happens very often if there is any ethanol in the fuel..............RC
Click to expand...

Hey Richard! Thanks VERY much for your input! Sorry it's taken me so long to reply, I got busy again. Finally had an opportunity to spend a few minutes on it tonight. Unfortunately, I don't really have many opportunities to do in-depth diagnostics anymore so I often end up throwing parts at it. Tonight I threw a new coil and module on it and there was no improvement.

After reading your post, I'm back to thinking it's a stuck injector. When I went through the injectors with a noid light (Sept 18th), the engine did start idling and running better, but still not right. I'm guessing I may have had two stuck injectors and now I'm down to only one.

If I find a stuck injector with the test leads as you described, can you recommend a procedure to "unstick" it?

Thanks,
Rob
 
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