Need some input -> Problem with 3.2 transplant going lean and misfiring after two min

[Wayne 962]

Originally Posted by cabmando

Am I the only one who finds it odd that cylinder 4 is running 30-40 degrees hotter than the other 5? When I get time I'm going to have to fire up my car and take some readings. I don't recall any of mine being that far apart.

Edit: You mention a few times early on that you measured temps and "they were all fairly even" (post 88, page 5). I haven't come across a post yet where you have temps. Just seems odd to me that the one is a good bit higher than the other five when the other five are all within 10 degrees.

I don't recall any of them being out of spec from each other - if you move the thermometer around, you can easily vary the temps by 30 degrees or so depending upon the temps on each pipe. I was looking at the camera when I took those photos, I didn't recall reading a super high reading. Still, indeed, that is something to look at there.

-Wayne

[Wayne 962]

Okay, so I cleaned up the fuel lines today and put the thing back together. To recap, in this latest iteration I did the following:

- New fuel tank, new fuel lines, new fuel filter, new fuel, Techron, new fuel strainer in tank.
- Had the injectors cleaned again. Had the injector rails cleaned.
- New plugs
- New air flow meter (AFM), and reconfigured the air intake to be straight.
- Cleaned up the engine bay, changed the oil filter.
- Replaced the intake manifold gaskets (12) and spacers (6)
- Smoke tested the intake for leaks -> none found.
- Drove the car hard with the Techron in the tank.

Bottomline? None of this made a difference. The car still has exactly the same issues. At idle, with the O2 sensor disconnected, the car runs lean and flubs / misses. After the long drive today where the car was run hard and was fully hot, the car was missing and flubbing at idle. If you increase the idle to about 1,200 the mixture goes back down to about 14.7 (correct), but the car still appears to flub and miss. Again, when starting cold, the car does not miss, does not flub, does not make any odd noises that I can hear (it's warming up at 1,100 or so rpm). As soon as it's warmed up, it sucks eggs.

There was one time while driving today when the car was idling, and it did not appear to have any issues. The engine was not missing, and it the idle mixture was indeed reading about 14.7:1. I thought at that moment, "oh, I have cleared out whatever was troubling it (carbon build-up, etc.)." But I was wrong - when I got back home, it ran *exactly* like it has before. I mean, it wasn't even slightly better this time, it was *exactly* like before.

I drove it up Crenshaw today, next to the long wall that is on the driver's side of the road - this is useful for listening to the car. It sounded a little off, like an exhaust leak or something like that, but I can't tell with the sport muffler (which I put back on). I do not have a "before" reference to compare to. I'm starting to consider if the engine has pulled or broken studs (I'd have to basically remove the entire exhaust to check - it's very difficult to remove the lower valve covers on the 914). But I very well know what broken head studs sounds like, and I don't think this is it. Even if they were broken, then that wouldn't really explain the flubbing at idle (broken head stud engines tend to make noise on throttle - not idle. Pulled engine studs make noise on idle sometimes, but pulled studs only really happen with the magnesium cases - this one is of course aluminum).

Speaking of driving, the engine appears to have a lot of power and doesn't appear to be weak. This is of course using the "butt dyno", which is notoriously wrong. While driving (with the O2 sensor disconnected), the air-fuel ratios appear to be exactly where I would have expected them to be (except at idle):

- Driving in a straight line at 3,000 rpm with about 1/8 - 1/4 throttle, the mixture was pretty much spot-on at around 14.0-14.7.

- Accelerating hard, the mixture richened up to the high 13s.

- Coming off throttle at high rpm like coasting down a long hill using engine braking, the mixture went super lean.

- Heading up that same hill at full throttle made the engine go to the mid-13s in mixture.

I will try to get a video of driving with the tach, the road and the air-fuel mixture together. Might be a bit difficult.

I took the temps of the pipes under the engine - none were completely dead, and some were hotter than others. I still have no idea what the baseline should be (some pipes naturally will run hotter than others due to the geometry, configuration and air flow past them).

I swapped Steve W's ECU back in tonight to check once again - it made no difference.

I'm pretty much out of ideas by now. I'm beginning to think this is a mechanical problem. Could be chain tensioners, although I'm not hearing rattling chains. I checked the cam timing, I'm fairly confident that it's within spec. I think I need to go back to basics (yet again), and pull the plug for each injector while the engine is running to see if there is any one cylinder that is missing. Then I need to get the thing hot again, and perform another compression check and a leakdown test (my tester hose broke last time I was doing the leak down test). I can also pull the spark plugs after this one run and see what they look like (maybe I will do that first).

I can run another smoke test on both the intake and the exhaust when the car is hot / warm. That would be fairly easy to do.

NOTE: Since installing the new air flow meter, I have not adjusted the mixture level off of the factory setting. I figured I would run the car hard with some Techron and see if there was some better results from (hopefully) cleaning off any carbon before messing with the mixture. The engine is running exactly like it was before, so I'm guessing there's nothing wrong with the AFM, and I'm also guessing that adjusting the mixture on this new one (the take-off from a Singer car) would have almost no effect like the the older one.

I haven't replace the TDC or the rpm sensors, but I fully checked them with the oscilloscope and they tested okay. That would be another $250 to replace, and there's no indicators that they are the issue.

Some videos:

First starting up, there do not appear to be any issues. It idles at about 1,100 no problem.



This is the problem in a nutshell. Nothing has changed. Idling like crap and the mixture is very lean:



So, this is interesting. If I raise the rpm to about 1,100 or so, the mixture comes back into line, but the engine is still missing. It doesn't disappear but it appears to get better. This may be why the idle was set so high by the previous builder - perhaps to disguise this issue. In this video I do the following:

- Let it idle (800-900 rpm), mixture is lean, I show the tach. Then I press slightly on the throttle and raise the rpm to about 1,100 or so. The AFM goes rich at this point to about 14.0-14.2. This is running in open-loop mode (no O2) sensor, and from what I understand is pretty much spot on, at this point.

[Wayne 962]

Okay, so I couldn't just go to sleep without pulling the plugs. Verdict, they all look okay. So, we have a situation here where the car was driven hard, brought back and let to idle for only a few min. So, this tells me (I believe) that the car is running well / fine on throttle / at higher rpm, and then mucking up / missing at lower rpm.

Which then begs the question, what hypothesis fits this fact pattern? Faulty distributor? Not likely, as there would presumably be problems at higher rpm (assuming that there aren't problems at higher rpm - we'll assume that for the moment based upon the feel of the engine, and the mixture readings from the LM-1).

How about the injectors? Is it possible that one or more injectors are not property operating at lower rpm? I'll admit I do not know enough about the complex operation of the pulse cycles of these injectors to be able to determine that. Tomorrow I can pull each plug from each injector (again) to see if any missing / flubbing goes away. I have some spare injectors I can swap in. Reminder, #1 was indicated as causing issues when it went back for cleaning (read "CLOSED" on the report, whatever exactly that means...)

How about carbon buildup on the valves? At lower rpm, then leakage past the valves would have a bigger effect. But the compression check came back okay - it shouldn't have come back fine if there were an issue with valves (I'll probably perform a leakdown test on Friday).

What about chain tensioners? When the engine misses, there are noises coming from the engine, but they are very soft and it doesn't sound like chain noise to me. Broken head stud - very unlikely to cause the issues / problems that I'm seeing. Actually, I just checked all of the lower ones from under the car - they are all there. No exhaust gas trails either from any head / header gasket issues.

Summary: seems to run fine through rpm, but 1,200 or below seems to miss and flub, but only after about two min of running (seems fine when stone cold). That seems to indicate that something is opening up when warm that could be causing issues.

I think the compression and leakdown test will be more useful information. In the meantime, here are photos of the plugs:

Plugs that I pulled tonight. They all look fairly good to me. These have about an hour's worth of heavy running time on them, 1000-6500 rpm, up hills, down hills, lots of full throttle pulls:



Close ups of each plug from the set. Although the lighting and angles of the photos may make them look like there's a big difference, there really isn't any discernible difference between any of them:





A composite shot of all six plugs. Again, while one may look darker or different than the others, it's pretty much a camera angle thing:





These are the original plugs that were 12+ years old:



These were the plugs from last month, almost exclusively idling time on these. I posted photos of these already:

[cabmandone]

- Driving in a straight line at 3,000 rpm with about 1/8 - 1/4 throttle, the mixture was pretty much spot-on at around 14.0-14.7.

- Accelerating hard, the mixture richened up to the high 13s.

See comment below about hill run


- Coming off throttle at high rpm like coasting down a long hill using engine braking, the mixture went super lean.
It will.

- Heading up that same hill at full throttle made the engine go to the mid-13s in mixture.

You'll have to wait for Steve, Sal, or Ingo to chime in but it's my understanding that even a stock chip should run in the 12's on a pull like you're describing here. I don't know how my chip is mapped but on that kind of run I'll dip into the high 11 range. I'm thinking you're pulling unmetered air when under heavy throttle or your injectors aren't feeding properly.

Edit: I'm probably way off on this but wouldn't setting the idle mixture at 14.7 when cold affect the mixture when it warms up? Somewhere I have a document that gives a number of turns from fully seated to get you in the ballpark then set the base idle once the engine is warm. I'm looking for that document. It just strikes me that your readings at WOT are off and that your issue is the base idle mixture is wrong when the engine warms. I know in my own instance, when my car had what sounded like a cam lope idle, I had a few leaks that needed to be addressed and my base idle mixture was WAY off.

Edit#2: FWIW, when thinking about how my 3.2 runs at cold start, my car will run about 13.8 AFR until it warms up then it settles in around 14.2-14.7 warm. My wideband setup is mounted in the car. I don't run an O2 sensor because my car has been tuned to run without one (Gotta love Ohio!) I set my base idle when the engine was warm.

[johnman001]

Sorry for not reading all 21 pages, but thanks for responding to one of my previous suggestions, but have you done a compression test on this engine? Also, when was the last time you adjusted valves?

You mentioned that your exhaust temps were uniform, but the pic I saw didn't look all that uniform. One header tube was much hotter than the others. I'm wondering if you need a valve adjustment or if one or more cylinders are low on compression.

Your injectors and plugs all look either new or recently tested, and I am assuming that you did a fuel pressure test so I am also assuming that your fuel flows are uniform. It appeared as if you did check your wires, your cap and your rotor (and possibly wear on your distributor shaft), so that must be in check. The DME controls timing and you reported changing that out with a known good one, so you should be good there. At that point, I'm thinking the possibility of something mechanical. If it is indeed on one side, could cam timing on one side be off from the other (chain, tensioner, set incorrectly from the beginning, etc.).

Do you have a video clip showing what it actually sounds like when first started and compared to what it does after a short time running? Could it be as simple as base idle not set correctly? (You know, with the idle stabilizer disabled using a jumper across pins on the diagnostic plug. They can and do run/idle wonky if this isn't initially set.)

Good luck with trying the "Italian Tune Up".

[3rd_gear_Ted]

Could too rich a condition for too long foul the O2 sensor??

[scarceller]

With the stock O2 sensor disconnected you should be at around 14.0AFR at warm idle. You should not be at 14.7AFR, that's to lean for idle in open-loop. Get the motor fully warm and set base mixture at idle to 14.0 +/-0.2 you will need to turn the CO screw in a bit (clockwise) possibly 2 full turns. At 14.7AFR these motors tend to lean mis-fire at idle.

The pictures of the plugs you pulled look like it's running to lean, they should not be that white, they should be toasty brown.

Then do a WOT pull as follows and watch the AFR, 4th gear 3000RPMs go for WOT and then ride the brakes slightly for a few seconds to hold the RPM near 3000, just do this for no more than 5 seconds and quickly make note of the AFR. A stock chip will be in the hi 11s to low 12s but an aftermarket should be in the hi 12s and never any leaner than 13.2AFR at WOT.

I sent you a data sheet with 7 testcases I have come up with from years of observing the 3.2L engines. Gather those 7 test cases and report back.

In Summary: you are still to lean from the above recent posts, turn that CO screw in a bit.

Does this motor have custom cams? Or is it possible the cams are not properly timed? Any history on this?

[scarceller]

One more quick test: with Engine fully warm and at idle make note of the AFR then unplug the idle switch and the RPMs will increase slightly but now make note of the AFR with idle switch unplugged. Doing this test will transition the DME from the idle maps to the part throttle maps but you are still at idle stop.

What chip are you currently using? I suggest you use a stock chip during all the troubleshooting do not use any aftermarket chip yet if possible.

[proporsche]

can you trust the Russian to make good spark plugs....???I only use made in Germany....if you can get them...not your problem but i did have problem with some of them ....
Ivan

[scarceller]

I just noticed those are WR7DC plugs, the 'R' means they are resistor plugs and you already also have restive ignition cables. They are the correct plugs by the 'book' but you should not use restive cables with restive plugs, you use one or the other not both.

I suggest you try W7DC plugs, these have no resistor in them, I have found they work better at idle and very lo-loads where lean mis-fires tend to occur. I don't think it's your core issue but moving to non resistor plugs is a very good idea.

[ischmitz]

I asked before. Maybe you have a flat cam or a wrong version of cam in one side of the engine. That would explain the differences between banks.

[proporsche]

Sal..can you get in US the euro Bosch w4cc for non cat engines?

Ivan

[Mixed76]

Sal thanks for posting, good info there.

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[Wayne 962]

Ran a cold compression and cold leakdown test today. Supposedly (depending upon who you ask), the tests should be worse when cold. Here, the tests are great. I ran them cold because I had the plugs out from last night and wanted to get my new tester configured properly - not on a hot engine. I think I'll install the plugs again, and warm it up and try again...

-Wayne

[Wayne 962]

Leakdown. Tested with 50 psi. Any higher and I can't hold the engine on TDC (it's a 914, and you just can't get a wrench on the pulley to hold it):








-Wayne

[Wayne 962]

Photo of the car:



-Wayne

[Steve W]

Wayne, first pull the mixture plug out of the AFM and adjust the idle mixture first to an AFR of 14.0-14.2 at normal engine running temp at the 880 rpm idle speed, with the O2 sensor disconnected. The proper way to remove the plug is to drill two small holes on the plug about 2-3 mm apart, just large enough to use a pair of needle nose pliers to insert into the holes to pull the plug out. Then report back on how it idles. Don't worry about where the mixture is at 1100 rpm for now.


I suspect you may need to loosen the spring wheel in the 964 AFM to get it in spec to what the original 3.2 meter was. That seemed to be my experience on the last one I received from a Singer 964 and tested on my 86 a couple of months ago. I forget how much I loosened it, but it may have been about 7 gear teeth. This will bring your full throttle AFRs to the high 11s/low 12s at full throttle after 4500 rpm, where it typically goes with a factory chip, vs your high 13s, which is too lean. You can also compare the tension of the door of your original 3.2 meter vs the 964 one and I think you'll notice it be be quite a bit stiffer. Try first by loosening the tension until it is the same as the 3.2 meter, then rerun your full throttle AFR tests and report back.

[Wayne 962]

Thanks Sal, I'm going to put the plugs back in and then record your test procedure.

I might not be able to get the rpms exactly correct with #4 and #5, and this is a 901-based gearbox installed in this car (not a 915 or G50), so the ratios may be a bit different.

-Wayne

[cabmandone]

Originally Posted by Wayne 962

Thanks Sal, I'm going to put the plugs back in and then record your test procedure.

I might not be able to get the rpms exactly correct with #4 and #5, and this is a 901-based gearbox installed in this car (not a 915 or G50), so the ratios may be a bit different.

-Wayne

You are ultimately trying to do what you did on that uphill run you mentioned previously. You are looking for a WOT run under some load.

[Wayne 962]

Just went out on that hill with my son on the iPhone video and the LM-1. Hmm, the under load is just plain scary fast. Measurements were in the 12s and 11s and 10s on full load. Right in the low 14s on the level highway, holding steady. Came back and the idle was way, way better - no missing, and the mixture was very close to spot-on. I'm feeling hopeful / optimistic that there were a bunch of small little problems (which I hopefully fixed) and that while I was messing with it, it gummed up the cylinders and valves with carbon, which I'm slowly burning off.

I'll post the video soon with some comments. I also have the results from Sal's test sheet here.

I might take it on an extended drive to Orange County tomorrow too - that would give it some good highway clearing out.

Fingers crossed!

-Wayne