7MGE sputters and bogs <2500rpm. checked stuff! Edit: SOLVED!!!

[3p141592654]

Gary's right, a video of this car idling would help a lot. I am wondering if the driveability description may just be off.

I just realized after rereading the first post that the EGR was already off and cleaned, so it seems pointless to further mess with it. The first post is a little unclear, did the OP check for code 51 at idle with TE1 grounded, or just using a meter?

Too bad this guy has an 89, the only year they cranked down on the HC spec to 85ppm for a manual. If he had any other year he would only need to pass at 106ppm, which he would have a great chance of passing with steps mentioned above.

By the way I am getting 17.5mpg driving 8 miles to work an back in the winter, so 16 doesn't seem out of the question for short city driving in winter.

 

[PureDrifter]

dont really have too much time to work on it tonight but i'll get you guys a video asap. I did forget to mention that the ECT sensor and re-timing the motor brought my idle down to the proper 650-700 range when warm, though it does have that odd sputter.

i just put ~27in. Hg on the EGR vac line at idle and got absolutely NO change in idle, going to see if i can hunt up a bit of alum. to make a quick 'n dirty block off to test the stuck EGR theory one last time...

 

[Nick M]

Edit: Beaten by 3p. Thanks Jon. I avoided typical causes of slightly elevated HC only because the engine running poorly with such good numbers interests me more at this point

Almost like a small fuel leak. Or a cat that just doesn't work good enough.

 

[PureDrifter]

video
[video=youtube;sQqfUHp5TeI]http://www.youtube.com/watch?v=sQqfUHp5TeI[/video]

warm start up (normal ops temperature before)
couple free revs up to ~6/6500rpm
idle (sputter/misfire very apparent)
~2000rpm hold (still pretty apparent, car was smogged at ~1.8-2k rpm and bogs/sputters)
idle
~4000rpm hold (less apparent, doesnt bog at this rpm)
idle


help please :1zhelp:

 

[3p141592654]

Well I am stunned that has the emissions profile you posted, it sounds like it is missing at 2000rpm, but the O2 numbers don't support that. Compression okay?

 

[SRZMK3]

have you measured the TPS to see if there is a dead spot at that point in throttle?

 

[PureDrifter]

Well I am stunned that has the emissions profile you posted, it sounds like it is missing at 2000rpm, but the O2 numbers don't support that. Compression okay?

a friend actually suggested that as well, will try to get compression or leakdown numbers soon.

have you measured the TPS to see if there is a dead spot at that point in throttle?

TPS is new and was adjusted with a digital multimeter, seemed to work well enough to get rid of the code 51?

 

[jetjock]

It's not your TPS. Like 3p I'm at a loss about the emissions though. Very strange...

 

[PureDrifter]

still need to borrow a compression tester, but in th emeanwhile i double checked the distributor cap+rotor (to make sure the rotor was oriented properly, it was). While in there i double checked the magnetic pickup air gaps ( from http://www.cygnusx1.net/Media/Supra/Library/TSRM/MK3/IG/IG_009.gif) and pickup resistances (all were in spec)

I did find, however, that the primary ignition coil circuit resistance was out of spec (0.6ohm vs the 0.24-.3ohm stock range). the secondary coil was within range at 10.59k ohms. could that possibly bad primary coil cause this maddening misfire?

 

[PureDrifter]

given the above (and a bit more research) i'm going to go ahead and see if i can source a replacement coil for cheap. (either Beck/Arnley stock replacement or MSD Blaster SS as they're the same cost)

all help still appreciated.

 

[3p141592654]

If it was me, I would followup with the pre-cat numbers. As JJ asked, what is the average O2 sensor voltage at 2000 rpm taken over the course of a few minutes? Also, what is the Vf voltage at the diagnostic connector during the same test. Since the catalyst can mask problems it'd be nice to know what the pre-cat numbers are.

I rather doubt your coil is at fault, since it is common to all the cylinders on a GE.

 

[jetjock]

I was going to say the same thing. A bad coil would effect all jugs. Plus coil resistance changes with temp. Plus it's tough to accurately measure resistance that low with a run-of-the-mill meter. I think his coil is fine but I suppose the cap or rotor could be at fault. If it were me I'd have scoped the damn thing by now even if I had to pay someone. At least then I'd know exactly what's happening and where. As for getting mean O2 I've given up on that...

 

[PureDrifter]

If it was me, I would followup with the pre-cat numbers. As JJ asked, what is the average O2 sensor voltage at 2000 rpm taken over the course of a few minutes? Also, what is the Vf voltage at the diagnostic connector during the same test. Since the catalyst can mask problems it'd be nice to know what the pre-cat numbers are.

I rather doubt your coil is at fault, since it is common to all the cylinders on a GE.

The Blaster SS was going to be a cheap upgrade for me anyways, $45-50 and i usually see a 0.5ish mpg gain which makes it (eventually) worth it on most cars.

I was going to say the same thing. A bad coil would effect all jugs. Plus coil resistance changes with temp. Plus it's tough to accurately measure resistance that low with a run-of-the-mill meter. I think his coil is fine but I suppose the cap or rotor could be at fault. If it were me I'd have scoped the damn thing by now even if I had to pay someone. At least then I'd know exactly what's happening and where. As for getting mean O2 I've given up on that...

i've had a rough time finding any of my shops that actually have an ignition scope, they all have the NEWEST diagnostic equipment for OBDII cars but show them anything pre 95 or w/o EMS and they kinda flounder

that being said, i believe i may have POSSIBLY fixed the problem, i am going to hesitate to say what it was (out of a combination of shame and trepidation as tomorrow it goes back on the rollers) until a day or two hence.

getting the O2 voltages honestly just totally slipped my mind, if by some evil curse/twist of fate the problem it isnt what i believe it to be then mean O2 voltages at both idle and 2000rpm will be the next bits of info i (figure out and) get for you guys.

thanks again for all the help so far!! most appreciated gents.

 

[PureDrifter]

it PASSED!

stupidest crap ever....when i went to pull the plugs out for the compression test (2nd time seeing the plugs since i put them in 2 months ago) and i see this:

:yikes:

swapped in another plug and lo-and-behold the car is running PERFECTLY.:evil2: I'm pretty sure that the cylinder was firing part of the time which is why it didnt give me consistent results when i was pulling the wire from the cap.

passed smog today, so in the end i must have been blind :nono: when i last pulled the plugs out to check them (need to stop doing that outside in the middle of the night...) and NO MORE MISFIRE!

thanks everyone (esp. JJ and 3P) for the help guys!

 

[jetjock]

Hmmm. Something about all this smells bad...

 

[PureDrifter]

hmm? meaning?

to clarify, the jacked up gap is probably caused by me not seating the plug right when installing it, not a manufacturer defect (plus i double check gaps when i install plugs)

 

[Nick M]

That would have caused a dead miss.