what is this symptom (ignition-related?)

[dgdsm]

Video:

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Can anyone tell what this symptom/behavior is? I think it maybe ignition-related but not sure. It happens intermittently, in the 2000-2500 rpm range. In this case, it's happening when driving up a hill with the A/C on, so a heavy load on the engine. It used to throw a CEL 44 when it did this a few months ago, before I swapped the transistor pack. Now it just manages to get out of it without throwing a CEL. It's OK when it lasts a split second, not so when longer.

I have also some MMCD logs around from when this is happening but don't see anything obvious. Any suggestions appreciated.

 

[dgdsm]

This happened quite a few times today. Attached is a piece of an MMCd log (text file) where it looks like it's happening. The TPS is constant at 32.9% while the RPM and TIMA is jumping up and down. It's a little bit like the problem in this thread.

 

[91Bomb]

This happened quite a few times today. Attached is a piece of an MMCd log (text file) where it looks like it's happening. The TPS is constant at 32.9% while the RPM and TIMA is jumping up and down. It's a little bit like the problem in this thread.

I viewed the video in the PM you sent and thought perhaps your MPI relay was clicking on/off/on/off etc but it was hard to tell and I suggested if you hadn't opened up your ecu to do that. Btw, not sure if it's just me but the video posted in this thresd says 'an error has occrred' so try reposting that so others can see it like I did because it's acually a good video.

 

[dgdsm]

There's some rattling in the background because of the tripod not being held down securely, and things shaking around a bit when this thing happens. I think I have some lifter tick, but I don't think I have MPI/ECU clicking which would be coming from underneath the radio. I don't think there's any of that in this video.

I installed an ECU I picked up from someone locally in October, which is nowhere near as damaged as what I replaced. Here's an image of one of the caps in it from October. I cleaned out some of the residue around January, but that's probably a 17-yo cap. The areas around the other caps seem OK.

I don't get 'an error has occured' when I play this video, so it others get this please let me know.

 

[rush2252]

It acts like a CAS is going bad and your losing ignition. It almost has to be the only thing that would cause an interruption would be a break in the signal from the CAS or on any other car the CAM or CPS.

Kolby

 

[91Bomb]

I installed an ECU I picked up from someone locally in October, which is nowhere near as damaged as what I replaced. Here's an image of one of the caps in it from October. I cleaned out some of the residue around January, but that's probably a 17-yo cap. The areas around the other caps seem OK.

Not as damaged? If it's leaking it's leaking so this ecu may be semi-bad and causing all your problems. Try to fing a fellow dsm'er for a quick test swap or I bought one myself on ebay with a 30 day money back guarentee and the guy told me I could return it for ANY reason for full refund which would be ideal for your situation. Also if the board is not badly damaged you might be able to have a dsm'er from this board or the other one re-cap it for you for cheap.

 

[dgdsm]

It acts like a CAS is going bad and your losing ignition. It almost has to be the only thing that would cause an interruption would be a break in the signal from the CAS or on any other car the CAM or CPS.

The CAS is actually the next thing that I've been suspicious about. Also there's oil leaking from underneath the CAS... probably a bad O-ring. I'm also not too sure about the harness.

OK I guess I have here a question... do you think this could be caused by oil leaks in/around the CAS? Basically I showed the oil around the CAS thing to a dealer a while back and he thought it was probably the O-ring. So I have this CAS O-ring around but haven't gotten around to replacing it. Also, a mechanic a couple of weeks ago did an oil change and he really retarded the ignition timing. I used to see TIMA at 12-14 degrees at idle and now it's at 7-8 degrees. It idles at 600-700 when at a stop, which I'd never seen before. The problem seems to happen more in hot weather.

 

[dgdsm]

The previous ECU had bad acid damage and the vehicle wouldn't start without a hotwire.... of all things going into the CAS. I don't know if/how much that damaged the CAS, but the vehicle hasn't been acting up like this until recently. I think I might have found someone in SoCal to recap the ECU, except that I have to get it over there ...

 

[DSM1G90]

you could try Motoguy's Garage | Home for your ECU.

Also, with the timing, did you do a base 5*BTDC with the ECU probe grounded to chassis? I can see why the oil mech did the retard since you were so far advanced - yet he prob didn't to the proper way to do timings on our motor/ignition setup.

 

[rush2252]

There is no way to adjust base timing on your car unless you have adjustable cam gears or unless he removed the timing belt. The CAS is similar to a distributor on honda and nissans in the sense that it has an Oring. My 240s distributor went bad when the o ring went it coated the internals in hot oil definately not good on electronics. You might take the cover off of the CAS and see if its full of oil.

I dont think the mechanic did anything with your timing I think the CAS is bad and thats why your seeing the change


Kolby

 

[dgdsm]

The mechanic did some other work (starter) and the oil change was on the side. I seem to recall his saying something about adjusting the timing and idle. But yes I'll now look at that CAS.

 

[dgdsm]

OK I've now replaced the O-ring on that CAS. The old one was hard and brittle and broke apart when I took it off. I didn't really see a way to take off the lid.. seems like the screws only turn in one direction. I also cleaned out some crud that was stuck in there around the seal area. There was also no hex nut on the bolt underneath the CAS and it was being held by the iron bracket that attaches to the throttle body, so I installed a hex nut on there after putting it back in (also a part sitting around for 2 mos). Also, when I look at MMCd with the ignition switch to the ON position without the engine running, the TIMA is at 5 degrees, so I assume that that's the base timing. Looks like the TIMA is now 8-9 degrees when warmed up at idle.

It does not fix the problem, but the engine seems to run a bit more smoothly. Maybe the symptom is reduced a bit but not completely. If the CAS itself were bad, wouldn't the ECU be throwing a CEL 22/23? Could this be a PTM that acts up when the temperature goes up (80F+) ?

 

[rush2252]

Its got to be CAS the tach wouldnt jump if it were fuel or any other issue. Just swap one used they run $15.00 and it should solve your problem. Im editing my post from earlier you CAN adjust base timing with a light and moving the CAS long day...


Kolby

 

[dgdsm]

OK guys, I got the ECU caps upgraded last weekend, and this problem (stuttering/bogging/hesitation or whatever) seems to be gone. Maybe the CAS circuits in the ECU had something to do with it. There might be some idle issue, but I think the idle is getting better as the ECU relearns some settings. I haven't checked the voltages around the CAS in a while, but I'm not really seeing a CAS problem right now.

About base timing I guess 5*BTDC in MMCd with the engine off is just a setting in MMCd. I'm wondering if grounding the ignition timing adjustment connector and then looking at the logger is a good idea.... or maybe I'll just have to get a hold of a timing light.

So it looks like the problem in the video is resolved. I might even be seeing a mileage increase. By the way there's a great thread about these types of issues here.

 

[steve]

About that previous TCU problem, I ended up finding basically a good TCU with an exact part # match in a junkyard. It seemed for all purposes to run OK, though it still has the original stock cap. I ended up throwing away the TCU with the burnt-out cap.

So now, after having driven the thing across the country ( 2000+ miles) with minimal problems, it's throwing CEL 44 again ?!?. It does it particularly going up a hill and is even stalling out, which it hadn't ever done before.

Do you know what this might be?

Could TCU electronics issues affect ignition? It might be doing this when shifting gears.

Since I've fixed CEL 44 before, I assume I can do it again... except it's a pain and the symptoms are a little different this time.

Well the symptoms are consistent with

2. Engine idles roughly or stalls
- Check spark plugs
- Check ignition timing
- Check ignition coil

in this thread.

I don't know though why it's throwing the CEL consistently at 2000 RPM.

The TCU is unlikely to be the cause.

If your getting a 44 CEL it's still the same diagnostic tree as before. You have to start from scratch because any part of the system could have gone bad since the last time.

It's not clear if the problem is intermittant and going away while driving clearing the code of if it says on.

 

[DSM1G90]

or maybe I'll just have to get a hold of a timing light.

A simple tool to have in the toolbox and will always be your best friend...

 

[dgdsm]

The spark plug wells area looks gunked up and the plugs seem to me worn and overheated. The coil pack, which I swapped back in November had primary coil resistances of about 1.2 ohms back then (alldatadiy says should be 0.8). When I checked the resistances now, the resistances at first were 1.3 and 1.7. After taking off the plastic caps to check those terminals and sticking the plastic caps back on, I hit those caps lightly with a hammer. Now the resistances are both 1.3 ohms. I think it might be a mix of things, but could the out-of-spec coil pack be the main problem?

I saw the CEL 44 problem one time before after upgrading the ECU caps (April), then not again since this past week. It was not intermittent yesterday .. the CEL would go away if I rev up to 3-4K rpm, the code gets saved in ECU memory, then the CEL comes back a little later if I go through that 2K rpm point.