Engine Service Connector not working - can't set proper ignition timing

It could be a transmission issue then. I'm not a transmission guy, but I'd start out by pulling the pan and replacing the screen/strainer assy. I'd also check for metallic particles in the fluid and on the pan magnets. If the fluid smells burnt and/or there's a lot of metal flakes in the pan, then you may need to visit a transmission specialist.

Okay I'm going to pull the pan and replace the strainer assy. Is it 4WD specific? Is this the right kit? https://www.partsgeek.com/gbproducts...+Kit+1987+1985

Thanks Tim!

Yes, that's it. That one fits all years and all models of US vans with auto transmissions. More details on this job can be found in THIS THREAD starting on post #14.

Update, transmission seems to be performing much better after changing the fluid and filter. It shifts more smoothly at the usual RPMs again and engages at lower RPMs in reverse like it used to. The true test will be to see how it performs in the cold.

Thanks again for your time and help Tim!

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Originally Posted by timsrv

With those codes we must be talking about an 88 - 89 van......right? Code 22 is an ECU Temp Sensor code, but if that sensor is bad the van will run REALLY bad, so I'm guessing that's an old code that wasn't cleared. Code #51 is almost always a bad TPS. I would recommend clearing codes, driving the van around for a day or so, then check codes again. If code 51 comes back I'd replace the TPS. Based on my experience with these vans, if the TPS has more than 100k miles on it or if it has an unknown history, I'd probably just go ahead and replace it. Keep in mind there's an adjustment procedure, so familiarize yourself with that before you do the job. I posted a video of how that's done at the end of the 1st post in THIS THREAD. Tim

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Hi Tim,

I have 212k on the odo. I did pick up a new TPS and haven’t installed it. It runs ok, shifts ok, has a slow take off from the light (maybe just a typical characteristic). What I am unsure of is if I replace the TPS do I need to see the timing again? I had it smogged and they had to set the timing as it was advanced for some reason. I’d hate to compromise any issues when I need to smog it again.

Replacing the TPS will not affect your base timing, but it can affect your advance. The TPS is an integral part of the electronic advanced system. If the TPS isn't functioning correctly it can disable the electronic advance. To test for this put a jumper wire in your "Check Engine Connector" and verify your timing is set for 12° BTDC, then remove the jumper and check again. If the electronic advance is working you should see the timing jump to ~ 20°. If it's not doing that, and you're getting a code 51, replace the TPS, adjust it per specs given, then check timing again with/without the jumper wire installed. Be sure to clear all codes and drive it for a day or so, then check codes again to be sure none come back. Tim

PS: I'd also recommend checking the condition of your EGR modulator. If the plastic shows signs of overheating, then it's likely your cat converter is plugged up. Tim

If it's hesitating/stumbling during acceleration, you should also check the rubber intake boot that goes between the throttle body and the Air Flow Meter. Check for tears between the ribs. Another way to check is to squeeze it while the van is idling. If the van stumbles and/or stalls when you squeeze, then it's almost certainly cracked and it's causing the acceleration problem. Tim

Thanks, Tim. Just did a through check, intake boot looks good, no cracks or tears and is pliable.

If I replace the TPS with a new one, and calibrate it per your video instructions, should I expect a change in timing? If not, them perhaps that will yield the anxiety when I get it smogged. I don't have a timing light, and I remember when I failed smog they said my timing was off and they set it and had to change the cat. They suspected the TPS, but they didn't change it as the emissions out of the tail pipe were good after the repair and there was no check engine indicator on the dash.

hey Socal87, I just replaced the tps on an 1988 5spd 4x4. Initially when I changed the tps, I did not know that the TPS needed to be set position per Tim’s video. I continued to set the timing to 12 btdc. But when I removed the jumper, the timing did not jump to 20 btdc. It was also throwing code 5-1.

I later discovered the TPS thread trying to trouble shoot why the electronic advance was not working. I went back and removed the TPS and set it per Tim’s video and reinstalled. This fixed the problem, and now the the timing advances to 20 Btdc. From my experience it will not change your base timing.

However, in order to do this you will need a multimeter that can check continuity, a .028” feeler gauge (or stacked feeler gauges that equal .028) and a Throttle body gasket (or make a gasket from gasket paper as they are no longer available).

Hey, thanks for that.. it really helps! I think I might give it a shot. I experienced the same and so did the smog repair shop-- when they jumpered it, it did not have any effect and did not advance. I have to get some feeler gauges and a gasket and playback Tim's video.

I pulled the codes on it (it's for an 87 4WD LE) and I got a Code 4, 6, and 11. 4 is related to the water temp sensor signal. I changed it out, but might still be bad. Not sure what 6 is related to and that one's new. I did wire up a starter solenoid bypass, so I'm not sure if that's related, but it worked- starts up no problem. And I got the 11 code, which I think is the TPS.

Yes, on an 87 code 11 is most likely the TPS. Keep in mind the electronic advance changes timing when enabled, but not the base timing. In order for it to run correctly, the base timing needs to be set 1st, then you verify the electronic advance is working by removing the jumper and verifying the timing jumps to ~ 20°. If your base timing is correct, but your electronic advance is not working, it will most likely fail emissions. However, it may be possible to change the base timing to make it pass emissions, but that would most likely create a bigger problem with drivability. If you're a hands-on guy, you need a timing light (nothing fancy, just a basic model). If you're going to use a shop, make sure they know what they are doing and they understand the old-school tech of distributor adjusted base timing with TPS controlled electronic advance. Tim

PS: If it's running but you have a code 6 stored, that tells me you have old codes stored and you need to clear them. FYI, codes don't go away when you rectify the problem, they only go away when you clear them. Clear the codes then see which ones come back, it's the only way to know you've still got a problem. THIS ARTICLE gives info on reading and clearing codes. Tim