91 Z34 still Sick, but now have free scan

[robertisaar]

long-shift is something that only applies to transmissions with a PCS(pressure control solenoid) in place of a vacuum modulator, such as the 4T65, but not the 4T60 or 4T60E.

engine abuse should only kick in at high throttle...

[portsider44]

tuner pro 6.zip

Here's a long tuner pro that put in zip file.

Tried to take around block but didnt make it far before it died. At the very end I disconnected the IAC & it did seems to change anything. However tuner pro still showed IAC counts moving? I would have thought it would show nothing at all. My enginge vac was 14" at idle & would go up to 18-20 at higher idle. FPR is still showing showing hig but that could be crappy guage.

Towards the end you will see volts drop when I turn on ac, headlights & applied brakes. At one point I would go high RPMS & it did not die for sometime.

Also I I a spot where big lag in depressing pedal & when the motor reacted. You will see a spot with very high TPS but rpms didn't match. The attempt test car had no power & is still not dropping into low gear even when manual put in low.

Take a look at the report & see if anything jumps out at you. If the IAC were bad could it really cause it to die out & have no power? Also why when IAC disconnected do the IAC counts still move?

[robertisaar]

looking at the log in a moment, but: IAC counts will still move as the PCM will still act as if it is connected.

voltage dropping with that kind of electrical load at idle is normal.

as for the trans not going into 1st: disconnect power from the PCM via both fuses, should be one in with the fuel pump relay near the left strut tower and another in the in-cabin fuse panel. remove both for at least 30 seconds and then plug them back in, that resets the PCM, it should then allow for the trans to go into 1st since i assume it's in default mode at the moment(3rd gear, which is no shift solenoid commanded on).

around what samples did the engine seem to not repond to throttle changes?

IAC being bad shouldn't cause any trouble at all when the throttle is opened, its when it's closed is when the IAC does quite a bit for engine speed.

[portsider44]

Look at TPS in the 8900-9100 range have some odd looking ones. 100% TPS & low RPM?

Also look at 11170-11600 range long high rpm & it did not stall? Normally when you get RPMS up it dies.

Also checked for spark & I have spark to all plugs. #3 looks a little stronger then 1 & 5. Also when you pull the plug wires on 1 & 5 doesn't seem to cause a miss, however on #3 when ou pul the plug wire we can hear the miss & it will start to idle rough.

When in gear it feels like severe miss firing. Feels like the car is running in limp mode, no power at all. I know I have fuel, know I have spark, maybe I need to run compression test & see what it shows. Timing belt was changed at 63K, now at 99K. When I took covers off the belt looked good.

What would it do if it jump 1 tooth?

[pocket-rocket]

It would probably run rough all the time if it jumped a tooth. I think Ben and I figured it up years ago that each tooth was about 12 degrees of cam timing. I have my 92 set at the modified cam timing (intake cams set stock, exhaust cams retarded 13 degrees) and mine lopes at idle. Pulling 1 and 5 and not getting a change is a problem, and I'm starting to wonder about your coils/ICM flaking out from heat soak.

[robertisaar]

sweet zombie jesus, 33 samples to get from 500RPM to 2900RPM at WOT?

the MAP shows believable values the entire time as well...

and jon is right, pulling wires and NOT getting a significant change is indicative of something wrong with that cylinder at a minimum.

i have to wonder if there are any severe exhaust restrictions? that could potentially this... if you want to pull the O2 again, you could leave it out of it's bung and attempt to drive it like that. if it lives, then there is something blocking the path out of the motor, like a cat.

[portsider44]

Yeah I am leaning towards the ICM & coils. Just havent had time to work on the car, as I was sidetracked putting a fuel pump in my truck & new battery on my wife suburban.

[portsider44]

I know there is no exhaust restrictions as the cat is very free flowing. I got the coils & ICM off but I think maybe I need to run compression before I look at dropping $$$ into ICM & colis. Looking at coil 2 have numbers (1/4, 3/6) the third does not. So I am guessing that two are the orginals & one is replacement.

otherthat one time the tps & rpms normally seem to be what is expected. When that happen it seem like a lack of fire/spark. SO I feel the TPS is working properly

All I know the ICM & coils is a pain in the butt to get too. I ended up taking out fans, exhaust manifold, one side of cross over.

Just don't know what to do at this part, dont want to drop $190 to replace the ICM & coils & still not have it fixed.

[portsider44]

I hope to do compression test on Thursday, but have a couple of questions, as I have never done one. First whill there be any issues doing the test with the ICM (with coils), front exhaust manifold. Also thinking of removing the UIM to make it easier to test the back 3.

Plus I guess I should pull the fuel pump relay so the injector will not spray. Should I put oil in cylinder? If so how much?

[robertisaar]

proper compression tests consist of this: the engine being warm(coolant temp at least a few tens of degrees above ambient), throttle wide open, all spark plugs out and making sure the battery is cranking the motor consisitently from the first to the last cylinder tested. you COULD remove the UIM, ICM, exhaust, anything, if it will make it easier.

[pocket-rocket]

Removing the UIM makes it easier to get to the back 3, and also eliminates the WOT portion as well. I would pull the ECM fuse and fuel pump relay. This will disable the ignition and eliminate fuel getting in the engine and plug wires shocking innocent by-standards, like your dog. The only reason to put a small amount of oil in the cylinders is to check ring condition. If you add (what, a tablespoon or so I think is the norm?) and the compression goes way up, you know your rings are shot because the oil just sealed them up for you- hence the raised compression.

[portsider44]

Well I went to Autozone & got the compression tester. Since the car was apart, ICM, Coils, Fans, Front exhaust. Warming the car was not an option. So not sure if any of my results mean anything.

So I pulled UIM, all plugs, removed ECM fuse & FP relay. Install remote starter switch & screw tester into #1. Turn motor over 3-5 seconds & gauge is bounces up to approx 170. Test the other five & all around 160-170 range dry, however they will not hold it at all? (maybe this is due not being warm?)

Then throw transmission funnel in #1 pour little oil & follow with test, which was 240, #3 260, #5 260. Got to thinking maybe took much oil was poured in #3 & #5. SO add a little more oil to #1 & it goes to 260. Now on to the back side except this time I am going to add the same amout of oil. SO I add 1 cap full of oil to #2 & it reads 235, same amount of oil for # 4 & it was 240, #6 after 1 cap of oil was 240. Now with the oil added all 6 would hold pressure at least for a little while. I think the main reason be hind the higer reading on #3 & #5 was due to too much oil.

Which leads me to think that my readings were all within a normal range for a car with 95K. So would that mean that:

Head gaskets are fine
Valves & cams are working correctly (no stuck or bent) as the cams are opening & closing as should be
Timing is not way off

Also plugs looked good pulling them out, so changing FPR & o2 sensor got rid of the very black rich running look.

So I know I have fuel, even though it still seems a little high (could be cheap gauge giving high reading).

Motor vacum at idle is pretty steady (testing at map where FPR line goes) at 14 & will go up to 20 as idle is raised. Which leads me to think I do not have a major vaccum leak.

Sensor reading from tuner pro all seem within reason (at least for me) so nothing that jumps out at you now. Prior to o2 replacement car would not go into closed loop & o2 were very low. With new o2 reading jump around & it will go into close loop.

Now the battery may be a little weaker at 2 months of not running, but the volts when running don't seem to be an issue. However on last start up car would idle good but had no power when trying to drive. Transmission still will not going into low (been like that a while, even before current issue started). Can't get 100yards down the street w/o stalling. Plus removing 1&5 plug wires doesn't seem to affect it much. Remove #3 & you hear & see the miss caused by removing the plug wire.

Now car will idle for extended times with out dying, however sometimes raising the idle will cause it to die. Some time it will restart & sometimes not.

Right now I am thinking maybe it could be ICM/Coil related. However does the ICM control anything after it goes into closed
loop? I know I have spark at all 6 but some seem weaker. Could it be the ECM?

If you were in my shoes were would you go next??

Thanks for taking the time to read this, I know it rambles a little just trying to get all the facts out to you.

[robertisaar]

the cylinders not holding the compression is normal, compression tests don't require the valves to be stuck in a closed position, so it will leak out as the motor continues turning.

the ICM doesn't really "control" anything, the ECM sends it a signal as to how much advance it should be targeting. removing the 1 and 5 wires and not having a difference is definitely a problem, but the trans not wanting to go into 1st would lead me to believe potentially the ECM is an issue.

[Schurkey]

the cylinders not holding the compression is normal, compression tests don't require the valves to be stuck in a closed position, so it will leak out as the motor continues turning.

Nope. The schrader valves in the tester should trap the compression. Defective schrader valves--or a bit of grit caught in one of 'em, preventing it from sealing--will make the tester needle drop.

[portsider44]

OK found out a couple more things.

1. My thoughts on the cylinder # was wrong. I thought the 3 cylinders closest to the front/radiator was 1-3-5, however looking at phot from another post 1-3-5 are the back ones. So every time before this post if I said 1-3-5 I really menat 2-4-6.

2. I got everything back together (except air box) & I had the ICM tested & it passed. I know these test are not alway 100%. I made sure to put the cools back in different location on ICM. I appears 2 coils were oem (marked 1/4, 3/6) & one was a replacement. I put the replacement coil in the 1st spot (leftside, plug 1/4). Had problems getting car to start so I ended up using starting fluid. Recheck for spark & I have strong spark blue/white spark that will jump approx 1 inch on 2&4. However number 6 is weak & will only work spark if you have right next to metal.

3. Front wheels off the ground was able to put in gear & shift through with no problems. Maybe not the safest or smartest things to do but I whas able to run car wheels spinning with out it dying. However I noticed when car is in neutral the wheels still turned?

Not sure what to make of the wheels turning in neutral, but I would think I am in need of a new coil for 3&6 (middle coil) I guess if I wanted to make sure it was the coil & not the wires I could swap the middle & right coil & see if the weak spark follows the coil or stays with the wires.

Also does the 3.4 have a limp mode?