Bad Miss followed by Loud clunk when restarting

[goody90q45]

Thanks for the loaner ECU. I really appreciate it.

I checked spark in #2 cylinder only and it is good (grounded against plenum). Bought a compression check kit this morning and checked #2 cylinder only- 160 psi. I know fuel is coming in. So now I've done the spark / compression / fuel test but only on one cylinder. Maybe the ECU is sending bad info? Should I do the same to all cylinders or is this enough info?

[Q45tech]

Check # 6 this seems to always be one of the lowest in the tests I've done.

Or wait until you swap ecu.

[goody90q45]

Measured spark and compression in cylinders 2 / 4 / 6 today. Had spark in all three plugs (grounded to plenum) and compression was 160 / 165 / 160.Cylinder 8 is a little tougher to get to so I opted out on checking it based on the results of the first 3 cylinders.

So I've got spark, compression and fuel (a little too much) in the bank that's causing me the problems. Jay's ECU is on the way and I'm anxious to swap it in to see if my ECU could be the failure.

I'm planning on doing the final check on the camshaft position sensor (CPS) tomorrow. I share 96QOwner's concern that we are talking about the same unit. Is the CPS (ecu code 11) the same as the CAS (Crank Angle Sensor) that Wes and Dennis are referring to? Do I need to scribe it before removal to help reinstall it in the same orientation? No clues from the FSM. Thanks for all your help.

[elwesso]

Mike the CAS=CPS..... Cam angle sensor, crank angle sensor, cam position sensor. all the same thing....... Cam Angle Sensor is the most specific and accurate nomenclature...

Crank angle sensor really isnt very accurate as it does technically sense the cranks position but by way of the cam... its hooked onto the driver side cam.....

As far as I know you dont have to scribe the CAS however you might put a mark so you can get your timing back where it was before.... obviously any time you remove it your going to want to check your timing and adjust if needed, however I would recommend making some sort of mark so you can get it in the sameish position.

[goody90q45]

Mike the CAS=CPS..... Cam angle sensor, crank angle sensor, cam position sensor. all the same thing....... Cam Angle Sensor is the most specific and accurate nomenclature...

Thanks Wes. Now that I know we're talking about the same thing there's a couple of good posts out there on checking the CAS. I'll see if I can fit it in tonight.

[goody90q45]

I recieved Jay's ECU yesterday and swapped it in, there was no change- Raw fuel is still pouring out the exhaust manifold and tailpipe . Thanks Jay for getting it up here so quickly. I'll get it back to you ASAP.

I also took out the CAS yesterday and checked it. As I rotated the main shaft you could hear individual injectors clicking. I had done the electrical check prior to this so it appears to be functioning properly.

So I'm still left with fuel feeding through the right side bank of the engine, filling all the cylinders. Any other thoughts on what the problem could be or what I could check? Thanks in advance.

[Q45tech]

Well you now know the CAS is working as is the ecu. Change that banks ignition control module and check the wiring harness under it. CHECK connector from ecu to ignition module.. we can assume that bank is not firing the plugs.

The ecu provides the +12 to 4 transistors [inside ignition module] and then to 4 coils.

What do plugs look like they will have to be cleaned before trying a replacement ignition module. Sure you got the ground lugs under the scews in wiring harness ?

[elwesso]

Well you now know the CAS is working as is the ecu. Change that banks ignition control module and check the wiring harness under it. CHECK connector from ecu to ignition module.. we can assume that bank is not firing the plugs.

The ecu provides the +12 to 4 transistors [inside ignition module] and then to 4 coils.

What do plugs look like they will have to be cleaned before trying a replacement ignition module. Sure you got the ground lugs under the scews in wiring harness ?

Tech the only problem is he said he checkedthe no 2 cylinder and it was getting spark? Maybe not enough...?

[goody90q45]

I've actually checked 2 /4 / 6 and have spark, compression and plenty of fuel. Emailed Jay this morning and he suggested looking at the injector timing circuit. I'm not sure what to check but I'll read the FSM and posts and be back with more questions.

I should be able to do the troubleshooting that Tech suggested tonight. Keep the suggestions coming. I haven't got my car running yet but I also haven't had to pay a mechanic $90/hr to troubleshoot. Sooner or later I will find the problem. Thanks NICO.

[elwesso]

Im really curious as to what (if any) insight a consult could give us... I think your on a roll though and we'd like to not do that if possible...

For my own good, here is what we know is not causing this problem.

- Lack of spark- lack of compression- ECU- CAS

So far, we havent ruled out the injector circuit past the ECU... Possibly a bad ground on just the passenger side?? RIght now I am posting this from the computer lab at school, when i get back i'll look at the FSM and see if theres any ground points that you could check... Still, i would think if a ground was bad, it would prevent the injectors from firing, instead of holding them open, which it seems apparent that may be your problem.

I was thinking one thing you could try is to unplug the injector subharness and see if it spews out fuel. Seems highly unlikely that all of the passenger side injector O rings woudl fail all at once, but you might rule it out?

Regardless, it seems there has been a sudden change in the electrical system that happened that one day when this happened to you... highly doubt it was due to the redlining regardless...

[Q45tech]

If the injectors were locked open it would only take 55cc/370cc/min x sqrt [34/43.4] /60= 9.0 seconds to fill the cylinder and hydrolock probably less.

[3Q Jay]

Im really curious as to what (if any) insight a consult could give us... I think your on a roll though and we'd like to not do that if possible...

For my own good, here is what we know is not causing this problem.

- Lack of spark- lack of compression- ECU- CAS

mmm, i'm not toally convinced on the spark yet. i agree it's good that Mike can get 2/4/6 to spark to the plenum, but do we *really* know what it is doing when under running stress? perhaps the voltage to fire plugs breaks down very quickly (sneak path in ignitor circuit to groun for example). long shot maybe, but wouldn't rule out spark just yet. Mike- I don't have a spare power transistor--might try Tyrone or somebody--they prolly got one to swap out and try.

[elwesso]

why not just swap the one from the drivers side and see what happens...

[3Q Jay]

good idea. might still run rough, but if the fuel went away on pass side and reappeared on driver's side that would be conclusive. I also thought about the 4 lower o-rings on pass bank. seems odd that all 4 would go at once though? shouldn't totally rule that out though, as Mike did have a lower o-ring problem on #7 about 6 weeks ago.

damn. i'm a nerd to know such detail about another memeber car's history.

[goody90q45]

good idea. might still run rough, but if the fuel went away on pass side and reappeared on driver's side that would be conclusive. I'm a nerd to know such detail about another memeber car's history.

You're not a nerd. Keep the ideas coming. I had already started to measure the power transistors per the FSM (EF & EC-218) when I read this post. I wasn't getting the continuity readings but when I reread the instructions it says to use an analog VOM, not a digital VOM. You are correct though, swapping sides would tell me the same thing. I'm on it after work today. I'll go buy an analog VOM also.

I can't help but think I've got a short somewhere causing the PS plugs to put out a weak spark. I'll check the spark on the left bank and compare. I did check all the fuses yesterday and they were good.

I'm getting close to taking it to a shop since I'm running out of ideas. I know they don't have a Consult analyzer, but will their equivalent be able to plug into my OBD1 and see the same data? I've seen a few Infiniti's (I,J) there lately and can't imagine they could be working on them without an equivalent diagnosis tool.

Jay- I mailed your ECU back to you yesterday. Thanks.

[1990Q45'r]

Pull injector tube and visually check for leak.1990Q45'r

[goody90q45]

Thanks for the suggestion. Please elaborate. Are you suggesting a fuel rail removal and pressure check?

[elwesso]

Thanks for the suggestion. Please elaborate. Are you suggesting a fuel rail removal and pressure check?

Yeah what he wants you to do is pull the fuel rail from the manifolds and then see if they leak when you pressurize it..... Obviouly check the power transistors...

I have a spare transistor up in my attic i think

I dont think that any diagnostic tool cna do what the consult can do... At this point, i dont really know if it would help?

[goody90q45]

Good news today. I got her fixed. It was the lower o-ring on injector 8. Same o-ring that I replaced about 6 weeks ago. I got to talking to a co-worker today who said that all the cylinders can fill with gas if the leak is bad enough. The lightbulb went on when I remembered that #8 FI did not have a pintle cap when I took it out and might have sprung a leak. I pulled the injector and the o-ring was laying in the bottom of the port.

I'm kicking myself for not completing the compression test on all 4 cylinders. I checked 2-4-6 but got lazy and assumed that #8 would be the same. If I would have checked it I would have found the problem a week ago. I'm kicking myself even harder because now Brian gets to flame me since he suggested in the very first reply to my post that I needed to check the compression.

I only drove it around the block on the test drive and parked it and changed the oil and filter. The oil was very thin and you could see the fuel dancing on the surface. I just got back from a 10 mile drive, no faster than 50mph, and I've still got some black smoke coming out the tailpipe with a slight gas odor. Are there any precautions (oil additives) I should take before driving much further or is this normal? I could very possibly have another leaky o-ring. Maybe I'll do a compression check on all 8 cylinders since the ornamental covers are already off .

I appreciate all the responses I got from all the members (9 of you and many more lurchers). I considered every one of your suggestions as I worked my way through this problem. Thanks NICO.

OK. Let the flaming begin. I'll be on the classified board trying to find a few pintle caps.

[elwesso]

A compression would be a good idea, but what good what that would have done to determine this to begin with? A leaky o ring wouldnt show up on a compression check!

[3Q Jay]

Mike-sounds like progress. don't mean to be negative, but i'm not sure you're done yet.

please explain what is missing on the injector--pintle cap? (orange plastic in photo)?



You may have this injector if you like. ohms in spec. had 105k miles of crappy california gas when i pulled it.

[maxnix]

GQ, these imageshack links are just showing as the old box with the red X in them.

[3Q Jay]

huh. shows up fine on my screen. what about pict of fy33 and g50 in driveway (rims thread)? did thatone do same?

[elwesso]

They work for me..... Brian, PLEASE tell me your not using internet explorer!!!

[Q451990]

I'm glad to hear that you got her fixed! I would do two or three successive oil changes with Dino oil and cheap Supertech (Walmart) filters. Fill, drive 10 miles, change again...

If the crank case had that much contamination you want to keep in mind that you don't get all of the oil out durning an oil drain... there's usually several ounces hiding in there.

Heath

[goody90q45]

Thanks. I'm putting everything back together this weekend and I'll change the oil again. Cheap insurance.

[maxnix]

huh. shows up fine on my screen. what about pict of fy33 and g50 in driveway (rims thread)? did thatone do same?

Nope, but I run pretty heavy pop up and ad blockers. Pretty locked down, but no spyware, viruses, etc.

Posts linked to Member's Rides work great. Just won't let me upload.

[3Q Jay]

Posts linked to Member's Rides work great. .

Please let me know how.

[3Q Jay]

hey everyone- we still need to help Mike out here-- in emails he and i have been trading, i find out he has now 2 out of 2 pintle caps missing (he hasn't pulled the plenum yet). WTF? mising caps is a new one to me, what would cause them to disappear?

Mike- are both of those the factory (light brown) injectors?

[goody90q45]

Mike- are both of those the factory (light brown) injectors?

Yes. The body of the old injectors was a light tan but I'm not sure if the color had just faded compared to the light purple ones that I've gotten from Joe. The new ones were purchased based on my VIN #.

Like I said in our email I'm not so sure if a previous owner hadn't removed them thinking they were a protective cover just for shipping. I suppose I might as well check #2 to see if there's a pattern. I'll be going under the plenum this summer when the days are a little longer.