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Old 09-03-2020, 11:29 AM   #101
bmdubya1198
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bmdubya, check out the last few posts in VolvOrr's thread. See if any of it applies to your situation. I saw in an earlier post that you're using an iPD cam. You might need at least an adjustable gear, or in a worst case a different cam.
Thanks for posting this! It sounds like his issue is very similar. I actually ordered an adjustable cam gear from STS machining last Friday, just waiting on it to ship. Hopefully it will be sent out soon so I can advance the cam timing a little bit. I really think that's the issue.

Some good points were brought up on that thread as well. I have no idea how much the head was machined on mine, I should ask the previous owner what the machine shop told him. My valve clearance is fine though, so I don't think there's anything to worry about on that end.
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Old 09-03-2020, 10:38 PM   #102
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Something came to me earlier... could this also have to do with a clogged cat? I checked the exhaust temp before and after the cat, and there was a significant (don't remember exactly, but it was around 50-60*F) difference with it being colder post-cat. The cat itself was around 450 degrees. The engine was off at the time, but I was running the car pretty hard about 10 minutes prior to checking the temperature. The turbo was still glowing right at the flange at the manifold... never noticed it do that before.

I also heard a rattle when I slapped the cat with my hand earlier. Couldn't tell if it was broken up pieces inside or it was something else rattling though.
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Old 09-07-2020, 08:07 PM   #103
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Pulled the cat today, it might be a LITTLE better but not too much. Vacuum actually looks a bit better at idle, closer to 15 in-hg. Still bounces around like crazy at idle. The cat was definitely backed up, you can barely see any light through it when shining a flash light into it and there was a good amount of debris in it when I shook it out.
Low end power may be SLIGHTLY improved, but I still think the cam timing should fix that. Still waiting on the STS cam gear to ship.

However there's a new problem... it's even worse to drive now. It decided to start misfiring under light throttle. Heavier throttle seems fine, but light throttle causes it to break up here and there while accelerating. This started midway through my test drive without the cat (open downpipe).

I also tried a known good MAF sensor today, no changes. Swapped in a spare dizzy cap after the misfire started, no difference.

Also, when I swapped the MAF and removed it from the turbo inlet elbow, there was smoke coming out of the tube. It smelled of oil... I think the turbo is crapping out. Any chance the turbo is the problem with all these vacuum issues? I have a 16t for it, but I still need to get a downpipe.
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Old 09-08-2020, 10:49 PM   #104
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Originally Posted by bmdubya1198 View Post
Something came to me earlier... could this also have to do with a clogged cat? I checked the exhaust temp before and after the cat, and there was a significant (don't remember exactly, but it was around 50-60*F) difference with it being colder post-cat. The cat itself was around 450 degrees. The engine was off at the time, but I was running the car pretty hard about 10 minutes prior to checking the temperature. The turbo was still glowing right at the flange at the manifold... never noticed it do that before.

I also heard a rattle when I slapped the cat with my hand earlier. Couldn't tell if it was broken up pieces inside or it was something else rattling though.
My experience with plugged cats are, the car will start up but die within 5-10 minutes, and if it does run it will terrible, and possibly run worse at higher RPM's.

I'm guessing you verified timing of cam lobes, piston position, crank, and rotor position/mark, and valve lash ? Did you mention inspecting the cam itself ? The reason I brought up timing again, was just to verify that your distributor has not slipped a tooth ?

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Old 09-09-2020, 01:25 AM   #105
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FWIW the ipd T cam left my 89 745 feeling underpowered until 3k or so until I advanced the timing to +4 on the gear (that's 4* advanced). Even so, it will not be as strong off of idle, but will have much more power to redline once youre in boost.

Did you ever resolve the low fuel pressure issue? 37psi is too low. Unplugging the FPR should increase fuel pressure by 10 psi or so. I have a few extra test rigs that you can install and hook under a wiper blade to watch while driving. Message me and you can buy/rent one.

The bouncing vacuum indicates an issue in the combustion chamber. There are some good basic infographics for diagnosing running issues based on vacuum readings that are probably a click away, or find some older school engine/machine shop guys to talk to. If you put a good head on the car, its not the valve train which would be my first thought. Do you still have too low compression on cyl 1? It might not be productive to continue troubleshooting until you have addressed that.
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Old 09-09-2020, 10:48 AM   #106
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Originally Posted by Otto Mattik View Post
My experience with plugged cats are, the car will start up but die within 5-10 minutes, and if it does run it will terrible, and possibly run worse at higher RPM's.

I'm guessing you verified timing of cam lobes, piston position, crank, and rotor position/mark, and valve lash ? Did you mention inspecting the cam itself ? The reason I brought up timing again, was just to verify that your distributor has not slipped a tooth ?

Everything looks good on the timing end. I didn't verify that the drive end is correct for the distributor, but I have a hard time believing it's not. iPd cams don't tend to have that many issues from what I've heard.

My cat was beginning to fall apart, so it's time to replace/remove it. I just need to figure out how to go about replacing it... I'm not equipped to weld (pretty much the only thing I don't do). Gotta find someone to weld in a straight piece of pipe for me.
Valve lash is fine, I triple checked everything before even installing the head.
Quote:
Originally Posted by adamdrives View Post
FWIW the ipd T cam left my 89 745 feeling underpowered until 3k or so until I advanced the timing to +4 on the gear (that's 4* advanced). Even so, it will not be as strong off of idle, but will have much more power to redline once youre in boost.

Did you ever resolve the low fuel pressure issue? 37psi is too low. Unplugging the FPR should increase fuel pressure by 10 psi or so. I have a few extra test rigs that you can install and hook under a wiper blade to watch while driving. Message me and you can buy/rent one.

The bouncing vacuum indicates an issue in the combustion chamber. There are some good basic infographics for diagnosing running issues based on vacuum readings that are probably a click away, or find some older school engine/machine shop guys to talk to. If you put a good head on the car, its not the valve train which would be my first thought. Do you still have too low compression on cyl 1? It might not be productive to continue troubleshooting until you have addressed that.
That sounds about right then as far as the cam. My adjustable cam gear finally shipped yesterday, so that should be here in the next few days. I figured it would need to be advanced a bit.

I will run another compression test though just to verify. I haven't checked all 4 since swapping the head, only cylinder 1, which was the same as before.

I'm really scratching my head over this cold start misfire now... the more time that goes by, the more goes wrong with this car. I just don't get it... I've gone over pretty much everything!
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Old 09-16-2020, 11:23 AM   #107
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Swapped on the adjustable cam gear, advanced it by 5 degrees, and it still feels the same. Kinda weird.

Anyway, I finally compression tested it hot on all 4 for the first time since I did the head gasket. Interesting numbers...

1- 103 PSI
2- 180 PSI
3- 190 PSI
4- 175 PSI

Cylinder 1 is definitely still low. I really think this is the rough idle. When I had the head off, I could see much less cross hatching on the cylinder 1 bore than the other 3 cylinders, so I'm assuming the issue is on the bottom end. I'm still debating on whether to just source another engine for this car or let it go... I have too many projects right now. It's a hard decision to make being that this car is so clean, but I would really like a wagon.

Anyway, I'm still confused over the hesitation/lack of power on acceleration. This was never an issue before. It wasn't until I started this thread that it became a problem. Aside from the bouncing boost gauge and rough idle, the car drove great up until then. Now I can use a calendar to calculate the 0-60 time.
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Old 09-16-2020, 09:28 PM   #108
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Originally Posted by bmdubya1198 View Post
Everything looks good on the timing end. I didn't verify that the drive end is correct for the distributor, but I have a hard time believing it's not. iPd cams don't tend to have that many issues from what I've heard.
I missed where you said it's an IPD cam

Those compression readings sound somewhat consistent with your earlier readings.


Last edited by Otto Mattik; 09-25-2020 at 02:51 AM.. Reason: take a guess
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Old 09-17-2020, 11:09 AM   #109
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They are pretty consistent with the original numbers, just showing that the problem is most likely on cylinder 1.

I haven't verified rotor position, but like I said before, this problem began before I installed the iPd cam. It kind of came out of nowhere, and I didn't notice it at first since I figured it was sluggish since I was running the AC, but when I stopped using it, it still felt like it was on. And I know for a fact that it's not running. The compressor clutch coil is actually shorted out now, so if I turn the AC on it pops the fuse within a few seconds.
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Old 09-17-2020, 12:40 PM   #110
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The dist on a 940 is idiot proofed
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Old 09-17-2020, 09:29 PM   #111
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Yup, impossible to screw up. Unless of course the cam itself has the slot cut in the wrong spot, but I find that pretty unlikely.
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Old 09-23-2020, 01:46 AM   #112
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What's next then ?


.

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Old 09-23-2020, 11:11 AM   #113
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From my findings with the compression, I think the only thing that makes sense is to source another engine. I've been tossing around the idea of selling this car, but I don't want to... clean turbos are too hard to find these days.
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Old 09-23-2020, 11:41 AM   #114
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Do a leak down test.
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Old 09-23-2020, 01:59 PM   #115
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Do a leak down test.
When I did one before doing the head swap, I was only hearing leakage through the oil cap and dipstick. It sounded like quite a bit.
And also through the turbo inlet, it was blowing smoke. Which happens any time after removing the charge air piping, but I'm assuming that because my turbo is totally trashed.
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