1993 Idle issues

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8/26/18 video of startup/stall: https://imgur.com/a/GpykD3K

Hey guys - lurked on here for a long time, just creating an account now to hopefully get some help with this head scratcher.

Bought a 1993 5cyl 5 speed back in May. Drove it 500 miles home suffering from some issues that the PO did not disclose, one being that the fuel pump would overheat and shut off after 90 minutes of highway driving. Also, the only fan operation occurred with the temp about 3/4 up the gauge (mid speed I think). But the van started normally, idled normally, and drove more or less okay.

Since getting it home I have replaced the fuel pump with the one offered by Europarts-SD. The install went off without a hitch. This fixed the shutoff issue and the engine seemed happier pulling up hills. Otherwise the van started and drove like it had, EXCEPT now it would occasionally fail to catch idle and would die. It would however immediately restart.

I didn't think much of it, it was happening maybe 1 out of 25 chances and the van is not my daily.

While trying to get my fans to come on when they should, I replaced the 2-pin blue coolant temp sensor (before realizing that it wasn't responsible for fan op).

We took the van from PA to DE and back, with the same infrequent stalling occurring. After coming home and being driven once or twice in 2 weeks, the van will no longer idle when started.

It will crank and fire up normally to 900 rpm, then bump up to 1100 or so before trying to settle back down around 900 and then dying. Sometimes it dies right out, sometimes it chugs a little before stalling. I can restart and repeat this over and over.

If I give it some pedal I can avoid the stall. I can also drive it away normally, and after being driven around it will idle fairly normally. But hot or cold, if I start it with the key, same results.

Since this has been going on I tried another new blue coolant temp sensor, and I have replaced all of the vacuum lines that I can see. Fuel filter and ignition wires look brand new, cap and rotor pass visual inspection. Haven't pulled spark plugs yet. IAC vibrates when it should, haven't cleaned it though.

I have unplugged individual sensors while idling with the following results:

CTS: Does not stall. Can be started with this unplugged and will not stall. Undrivable unplugged, way too rich

IAC: Does not stall, starts but then stalls faster and more violently

TPS: Stalls immediately

IAT: Does not stall

MAP: Disconnect and plug vacuum line, does not stall

Any ideas?

[Roby466]

We had the same issue with our 94 2.5 5 speed. The shop ended up diagnosing to a bad ecu and only the same ecu model could be used they said. We drove it for over a year having just pulled the throttle cable adjuster a notch. I know this was not a proper fix but it made it driveable. We sold it like that having fully disclised the issue and the guy was going to try sourcing an ecu. I hope your issue is a bit of a cheaper fix.

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[Roby466]

If the van is not your daily check with a tuner like Malone tuning if they can test or repair the ecu. If they can it might be as simple as shipping to them. Or find a good ecu and have them flash for your model/year.

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An update - sent out the ECU to be checked and rebuilt. Issues still persist - now engine starts and the revs only go to about 500 rpm.

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Ebay ECU rebuild did nothing and was probably a sham.

ECU was still throwing a "No MAP signal" code.

Installed a used ECU and the van is running fine again.

[postjosh]

sorry to here what you went through but glad it's sorted now. my '93 is a little up and down (bet 800 & 1200 rpm) on the idle but usually doesn't stall. gets better as it warms up. i've just been slowly going through maintenance things (e.g. pcv valve, plugs, air filter) and it's getting a little better. i'm going to do a new fuel filter soon. i'll probably clean the maf sensor, too.
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'93 EV Wkndr – 5 cylinder – 5 speed - 280k+ miles