Dave's Winter 88 Behaving Badly

[2seater]

I cleared codes on Sunday when we were looking at it, so it is interesting that there were ECM codes recorded in the last couple of days, although I don't see them as relevant to what is going on.

Would disconnecting the coolant temperature sender prevent going closed loop? I know there are some timers and other things in the ECM to help get it into closed loop for emissions reasons. I am not certain the lack of O2 sensor keeps it in open loop, but it seems to have done so on the red car that we rescued last year. We swapped ECM's in that case, and cured the issue, but found later, that if we switched back to the original ECM, it would also go into closed loop. From that information we assumed the connection at the ECM was at fault.

When we were looking at the inlet air temperature sensor, disconnecting it caused it to indicate full cold, like well below zero. Perhaps the coolant temperature sender disconnect would do the same. In other words, lie to the ECM.

[DAVES89]

I have extra ECMs and I thought that it might be a better test to swap a different one in keeping the original prom. Wasn't that bad as I used the tutorial in the "How to" section. Anyway, swapped one in and took it for a ride. Drivability was much better however at higher RPMs under hard acceleration it does start to buck, but no where near what it was before. I then thought that I would try a different ECM with a different prom and the bucking came back as before. So for right now I am leaving it with the original prom and the different ECM and see what happens. At any rate while not perfect I got most of it back.  

[Ronnie]

3 hours ago, DAVES89 said:

Drivability was much better however at higher RPMs under hard acceleration it does start to buck, but no where near what it was before.

I was hoping you were going to say it was fixed. Sounds like you have made a big step in the right direction.. If you haven't done so you might want to check all the dedicated grounds behind the battery to make sure they are clean and tight.

[Ronnie]

Any change in the way it is running? If it still does it only under hard acceleration that might be a separate problem like a spark plug or plug wire. Can you get it to do it if you hold the brakes and load it up without moving?

[DAVES89]

I drove it all day yesterday [about 200 miles, mostly interstate with some small town driving]. The drivability was very good and the bucking hardly noticeable. I did swap spark plug wires and Mass Air Flow sensor when this all started and will do the plugs as well as clean up the connections behind the battery as you suggested. I have a new 02 sensor and could install that if you think, but we did test the old and it seems to be doing it's job.

I can't remember, how did we land on the ECM needing replacement so fast? The replaced ECM is out of it's holder and is zip tied to the bottom of the dash and off the floor. I'm going to leave it out for a while to see if I am on the trail of an answer or if I have to do something else. 

[Padgett]

If it is an 88, there was a TCB on a replacement PROM (ANCX) that cured a number of things. BTW if is forced to stay in open loop, it runs richer than in closed. Len operation strains the secondary ignition.

 

BTW to be able to watch/log multiple data points at once you need an ALDL scanner and connector like TunerPro RT. it and an adapter are avaulable on Moates.net.

[DAVES89]

I think I have an ANCX if not Kevin [kdirk] does.

[DAVES89]

Just brainstorming here, does any of the ground wires in the race under the passenger seat feed any of the electrical boxes? About 3 months ago I tinted my carpets and used a lot of carpet spray with water in it. I've not had any issues with any other systems but maybe this is just the start?

[Ronnie]

1 hour ago, DAVES89 said:

does any of the ground wires in the race under the passenger seat feed any of the electrical boxes?

Do you mean the silver boxes like the ECM?

[2seater]

I should never say never, but I do not believe any engine wiring is routed under the seats. I know there were definitely harness routing changes between the touchscreen cars and the conventional style, but all the ECM grounding is done between the firewall and under the hood. That said, I went through the ECM pinouts when I wired one to use on my flowbench for testing MAF's and there are multiple ground wires in the harnesses that connect to the ECM, maybe four or five. There is a large ground stud kind of buried near the rear passengers corner on top of the engine. It is near the intake manifold but it actually threads into the head. At least on the later models, much of the top of engine harness, injectors, MAF, TPS etc... connect to that stud. The isolated grounds (ECM?) are behind the battery and of course the ground under the ignition module and on the radiator header near the battery, all connect direct to the battery.

[DAVES89]

1 hour ago, Ronnie said:

Do you mean the silver boxes like the ECM?

Yes I do mean the silver boxes. And sorry to say I have not yet acted on your idea to check the terminals behind the battery.

[DAVES89]

After I posted last I went out and cleaned all the grounds behind the battery as well as on the radiator area. I also cleaned the contacts points on the battery cable as well as the battery itself.

 i believe [as does Padgett] that I am dealing with a secondary ignition issue that rears its ugly head when the engine is warm. I think I am going to try the crank sensor next.

[DAVES89]

Spoke to Kendall [my mechanic friend] last night and he suggested I take a look at two items, the TPS [Throttle Position Sensor] and the EGR valve. I am leaning towards the EGR first because the throttle has excellent response when the engine is cold with no bucking. The EGR however is "out" of the system until the car is warm and then steps in to help with emissions.

I am able to "override" the EGR through the touch screen and will do that today. I really hope that is it as have 3 more in the parts bin that were all removed from Reattas I had parted out after driving them so I am sure each one works.  

So far I have swapped put the Mass Air Flow sensor, spark plug wires, Ignition Module/Coils and cleaned all the ground wire connections [behind the battery, the ones near the radiator, and the battery connections]. 

Another idea Kendall had was to replace the water temperature sensor. I don't believe that is the issue because I see the water temperature on the gauge page fluctuate just as it should going from "cold" to operating temperature to as high as 208 and then back down to where it stabilizes at around 195  

[DAVES89]

Okay ran it in override and E02 rough idle, E03 slight rough idle, E04 smooth idle so I am guessing I have complete blockage in 02 and partial in 03. Does that sound right or is it backwards?

[Padgett]

More likely it is leaking than blocked. The Exhaust Gas Recirculation valve feeds exhaust gas into the intake.

[DAVES89]

So I should still replace the EGR and not the Exhaust Gas Recirculation valve [that I never heard of]?

[Ronnie]

1 hour ago, DAVES89 said:

override and E02 rough idle, E03 slight rough idle, E04 smooth idle

Dave I will test my EGR and see what results I get when using overrides. I will test with engine cold and warm in closed loop. Will post the results in a little while.

[Ronnie]

Here are the results I got testing my EGR valve using overrides in diagnostics.

 

Before starting engine after sitting overnight all 3 EGR valves will click when pushing the overrides buttons.

 

On cold startup and entering diagnostics with engine running. 

ES02 (EGR Solenoid #1) - Rougher than normal idle

ES03 (EGR Solenoid #2) - Rough idle with some stumbling

ES04 (EGR Solenoid #3) - Really rough idle and stumbling badly

 

Engine warmed up to 170* with "loop" light lit and O2 sensor light flashing with engine running

ES02 (EGR Solenoid #1) - Rough idle but still keeps running.

ES03 (EGR Solenoid #2) - Rough idle and stumbling like it wants to die but will keep running

ES04 (EGR Solenoid #3) - Stumbles badly and dies in a few seconds

 

I checked several times with same results and verified the override numbers I posted are correct.   Seems our readings are opposite as far as the override numbers. Could you test again using the same override numbers I posted above?

[2seater]

ES02 through ES04 should get progressively worse idle or even stall the engine at the top. If not, something is stuck or passage is plugged with carbon. 

[Philbo]

So this might be a little left field, but could it possibly be the catalytic converter going bad?