spike1856

In the space of a day I went from an intermittent Code 32 (no big surprise with these cars, it seems) to Codes 32,33, 34 and 42.

The 32 I'm not too worried about. The EGR seems to be working perfectly fine, and I've been dealing with the 32 for about 11 months now, without any real problem.

I don't think the 42 is related to the 32/33/34... could anyone tell me what to do for that one? Chilton's says it's the EST, but doesn't tell me where that is for my engine (88/89 2.8L MPFI). It does say that for OTHER engines I would want to disconnect it when setting timing, and that would give a code 42... so does it seem possible that maybe mine managed to become disonnected? Would the engine even run if the EST wasn't connected? It seems to be running almost the same as it always has... I'm not 100% certain what the EST even does.

And for the 33/34... aren't they opposites? I'm not sure when I've gotten each, but I know that I have in fact gotten both of them in one day. I cleared codes one morning, then drove to school, got an SES light for the second half of the trip, and didn't have time to check the codes. After school I went home, again had the light for about half the trip, checked the codes, and saw all four of them were back. (This trip is 54 miles roundtrip, so it had plenty of time to pop any trouble codes it wanted ) My main question here is, aren't 33 and 34 opposites? Doesn't one mean too much of something, and the other mean too little? Seems strange that I'd get both in the course of one day. Any ideas?



Oh, and one more question--on the way home the other day, sometimes I'd be driving along (at freeway speeds, 55-65) and the car would start feeling like it was surging back and forth. The tach would stay steady, the engine would sound like the revs were still steady, but the car would definitely feel like it was surging. Should I start looking into getting the transmission rebuilt, or is there something else that would do that? I haven't driven the car since the surging issue started...

Sorry about so many questions, but problems seem to come in bunches.

snakeskinner

okee dokee, I don't know exactly what a code 42 is for a 2.8 MPFI but I believe it would be the same as for a v8 car. the EST is the electronic spark timing control by the computer. The EST advances or retards timing depending on what the ECM requests. by unplugging this bypass connector, you send the distributor into straight up timing with no advance, same as unplugging a vacuum advance on an older engine. This is to set the base timing. the emissions label under the hood should say where this bypass is at, the v8 cars bypass is near the evaporator case breaking out of the harness. Normally it is a tan wire with a black tracer. If you disconnect the battery to clear the codes and this code comes back, then you need to find the problem. As for the code 33/34, it really depends on the engine because a speed density vehicle is different. For a MAF car, 33 is for when the ECM sees a higher airflow reading than it thinks it should, 34 is a low airflow. You can definitely have both codes at the same time. I would first check to see if the MAF is plugged in. The surging could be caused by the problems you have. Improper timing, EGR problems or MAF problems could definitely cause a surge.

spike1856

Alright, I'll go have a look for the EST right now. This morning we topped off all the fluids, cleared the codes, made sure the MAF was connected well (it already was though--so that wasn't the problem with it) and drove it around for a short while. The surging didn't happen, but it wasn't happening often enough to expect it in a five-minute drive. The only code we ended up with after the drive was a 42.

Now, the surging... timing/egr/maf would cause surging, you say... but wouldn't it cause surging RPM's? The tach doesn't go up and down, and the engine sounds the same, the car just feels like it's going back and forth a bit. So would those still be possible culprits?

Thanks for the help!

snakeskinner

it's hard to say without actually experiencing what you're talking about. prettymuch any surging could be seen through the tach, even a tranny problem since it would more than likely be due to slippage. Some problems can be felt but not seen through things like the tach.

Slade1

Well the EGR really does serve a good function, it sends exhaust gasses back into to bring down combustion chamber temperature so no nox is formed. However it also has an added benefit that you can run it lean when its active...

Now here's where EST comes into play... on highway and consistent conditions the ECM leans out the fuel mixture for highway milelage. It also advances timing as well due to the consistent air flow in and out. To counter the obvious effects of pinging due to a combo of advance timing AND lean mixture, the EGR is opened.

That's how its all interrelated.

If the EST or the EGR is malfunctioning, it can't advance the timing nor lean out the mixture properly. The knock sensor goes off the scale due to pinging and then retards the timing... not 1 degree not 2 degrees but as many as 8 degrees, it can't back off timing like it advances it. So your rpm may be consistent, but you feel surging because timing and fuel mixture is constantly changing by dramatic amounts.

spike1856

This morning we found a couple loose vacuum lines, but we think we knocked them loose yesterday while we were working on it. We hooked them back up, cleared codes and drove for a couple minutes again, and got the 42. After about an hour of trying to find the EST bypass thing (the emissions label is wonderfully vague about where to find it--"it breaks out of the engine harness conduit"), we finally found it stuck behind a wire loom. The bad news is, it was connected perfectly well, so that wasn't/isn't our problem. What else could it be? Could the actual EST Module be shot? It's in the distributor, right? So I'd have to pull apart the distributor to check on the EST Module?