[B5 Money Pit]

1.8t 02, 230k mi. Just started this infrequent issue. Usually happens while waiting at a stop light just as pulling away. Very short but significant stumble, quick recovery. Stumbled once while cruising on freeway. This morning a random stall waiting at a light. No warning, just quit but fired right back up without hesitation. No misfire codes or MIL.

Thoughts? Injectors? Plug wires? MAF?

 

[ylwagon]

Start looking into fuel pumps.

 

[B5 Money Pit]

Just stalled again piulling up to a stop sign. Fired right back up. Now EPC light is tripped. But no more issues on the 5 mile trip home. Will go look at codes.

Fuel pump crossed my mind, but now with EPC on, I wonder.

It's not like a fuel starvation stumble or die. When it quits it just quits, sputter or stammer, just running then not. The stumble feels like that also, not like a starvation thing, more like just a quick shut off and immediately back on with no other hesitation or sputter. No warning lights when it happens, except for EPC now, no MIL.

Electrical? Ground fault? Cracked hose?

 

[B5 Money Pit]

OK found this on the scanner: P0688 / 17072. No other faults.

"ECM Power Relay Load Circuit Open."

Is his brain short circuiting?

Ross-tech wiki suggests that's a possibility.

Where do I find the relay for the ECM, to rule that out as another possible culprit?

 

[Tomvw]

The ECM power supply relay is a likely culprit, it is in the ECM box under the hood.

 

[B5 Money Pit]

The ECM power supply relay is a likely culprit, it is in the ECM box under the hood.

Thanks, Tom.

I opened the ecu box today. Nothing looked out of the ordinary.

The 15 Amp fuse and relay 429 seemed ok.

I cleaned the connector contacts with some DeoxIT electronic contact cleaner, they were a bit oxidized. I sprayed a small amount of cleaner up into the relay case from the tiny hole underneath, and shook it up a bit, then a bit of canned air to get out the cleaner.

At least my efforts didn't make anything worse, but we'll see if it helped anything, I suppose.

Can these relays be found anywhere but used channels, if it keeps acting up?

 

[Tomvw]

It is a typical relay available from most parts stores.

 

[B5 Money Pit]

Well, after cleaning out the 429 relay with DeoxIT contact cleaner yesterday, I took 5 mile trip to the store. Ran fine, no problems. Decided to drive it to work this AM, 20 miles mostly freeway. No problems at all. We'll see how the home commute goes, but this is looking promising.

I think I may try to find a spare 429 relay, just in case. :wink:

 

[Tomvw]

They're only about $10 or $20, I suggest you replace it before you are stranded.

 

[B5 Money Pit]

Still trying to find a spare #429 relay. Is a #30 compatable?

Meanwhile, the motor is continuing to behave wonderfully since I cleaned out the original relay with the contact cleaner. No stumbles or stalls at all.

 

[dav1129]

Thanks, Tom. I opened the ecu box today. Nothing looked out of the ordinary. The 15 Amp fuse and relay 429 seemed ok.

I cleaned the connector contacts with some DeoxIT electronic contact cleaner, they were a bit oxidized. I sprayed a small amount of cleaner up into the relay case from the tiny hole underneath, and shook it up a bit, then a bit of canned air to get out the cleaner. At least my efforts didn't make anything worse, but we'll see if it helped anything, I suppose. Can these relays be found anywhere but used channels, if it keeps acting up?

Well, after cleaning out the 429 relay with DeoxIT contact cleaner yesterday, I took 5 mile trip to the store. Ran fine, no problems. Decided to drive it to work this AM, 20 miles mostly freeway. No problems at all. We'll see how the home commute goes, but this is looking promising.

Glad I found this thread. I am experiencing similar if not the same, hesitations issues although never stalling. I may have had or still several things going on because I replaced the MAF and the hesitation although still there and sudden seems not as bad as it was. PZ suggested it might be my ECU replay as well. So I am really hoping it is. Where am I likely to find it though on a 1998 AEB?

 

[Tomvw]

It would be better to start a new thread with all your details.
The AEB doesn't have that relay.

Edit: The AEB does NOT have an ECM power supply relay.
Start a new thread, I am not wasting any more time on this thread.

 

[dav1129]

It would be better to start a new thread with all your details.
The AEB doesn't have that relay.

Doesn't have 429 replay or ECU relay? If it does have an ECU replay, I think I may have narrowed 30 or 460 or part number 165906381?