1998 Impreza TS Ignition problems

[Athowhen]

SOLVED:

Damaged signal wire at MAF connector.

 

Hi,

 

I'm just hoping someone has seen this problem and can tell me where to look before I start replacing thing$.

 

Symptoms:

Engine dies momentarily under acceleration from rest or slow traffic.

Feels like it would if i turned the ignition key off and on quickly.

Usually happens a couple of times then goes away once up to speed.

Can result in a complete stall.

Restarts normally.

No Error codes on OBDII

 

Conditions:

Engine is at normal operating temperature.

Always happens after being stuck in traffic or at a long light.

Dry roads, temperate weather.

 

I feel like this is a heat related component failure. ? The engine compartment gets hot dew to a lack of air circulation while stopped or moving slowly, then cools off when up to speed? I think its ignition because it all dies cleanly no spluttering or misfiring. There is a service bulletin about mild hesitation after idling (ECM misinterprets knock sensor signal and retards timing). But there is nothing mild about having your engine stop wile you're in first gear, so I don't think that's it.

 

Unfortunately I can't get a wiring diagram for the 2.2L engine so I don't know what the potential failure points are in the ignition system.

 

Any Ideas are appreciated.

Edited February 27, 2011 by Athowhen
Solved

[Olnick]

I had a similar stalling problem years ago. Replaced the Engine Coolant Temperature Sensor (ECTS) and it's been running smoothly ever since.

[Athowhen]

I had a similar stalling problem years ago. Replaced the Engine Coolant Temperature Sensor (ECTS) and it's been running smoothly ever since.

 

Thanks Olnick,

 

Do you know a diagnostic test for the sensor?

[Olnick]

Wow, you sent me on a search way into the past! Came up with this oldie-goldie:

 

http://www.ultimatesubaru.org/forum/showthread.php?t=89128

 

But now that my memory was jogged I realized that my symptoms were different. Car would stall when warm in traffic but would refuse to re-start. Also cleaned the IACV at that time and the problem went away.

 

In short . . . I may have been of no help to you! Sorry.

[Athowhen]

So I guess the ECM wont let the engine run if it's too hot. The temperature sensor fails in a low resistance state indicating high temperature. For this to match my symptoms there would need to be an intermittent short in the temperature sensor circuit, so this is not a likely candidate.

[Olnick]

Okay, let's start with some basic information (what I should have done to begin with!)

 

How many miles on the car? How long has this been happening? Did it start suddenly or just slowly get worse over time? Does it idle okay?

 

Any work done on the engine around the time it started? Had a tuneup recently? New plugs and wires? Filters?

 

Thanks, Athowhen.

[Fairtax4me]

I had a similar problem. Well maybe. Mine would just straight up stall. Like I turned the key off. Would do it at idle, at speed, in any gear, or just sitting still. Would restart and run just fine until it decided to die again. MAF sensor had a broken solder joint. I also had a CEL and P0100 DTC though.

 

Olnick asks the right questions. Answers to those will help the troubleshooting process.

[Athowhen]

OK, update.

 

The symptoms had ben getting more frequent the last few days and now the car won't run. It starts idles for a few seconds then dies again. I still think this is ignition related because of the way that it started to fail.

 

I was looking at prices for the coil pack/igniter $179 CAD, and saw a note "Please check the crank sensor for proper operation"

I managed to find a service manual on bit torrent, that has the diagnostic procedure for the crankshaft position sensor. I'll work through that tomorrow. If it's good I'll buy the coil/igniter pack. There really isn't anything else in the ignition control circuit, except the ECM.

 

The sensor check consists of checking the wiring harness for god conductivity and checking the resistance of the sensor. 1k to 4k ohms it's good, otherwise replace.

 

Note: this car is a 98, but it has the combo coil igniter pack that is found in the 99.

[Athowhen]

SOLVED:

Damaged signal wire at MAF connector.

 

 

I ordered the ignition coil form autopartsway.ca, installed it, no joy. Car started, idled up for 10 seconds, then died. This time I got a DTC P0102 "mass air flow sensor low input". This makes sense to me because I believe the ECM wouldn't use the MAF during startup (the engine could start without a signal from the MAF ?).

 

I bought a used MAF from a scrap yard, Car started ran good, then the symptoms described above began to return on the test drive.

 

I put the original MAF back in. The car started and idled OK.

 

Aside from replacing the coil, a problem that had now been ruled out, the only thing I had done was disconnect stuff. I started wiggling connectors while the engine was idling, sure enough, when I poked at the connector on the MAF the engine stumbled and died. On closer inspection, I saw that the insulation of the signal wire (red wire on right looking down on the connector) was broken. When I tugged on the wire, the wire broke easily.

 

I was able to remove that pin from the connector using a flat jewelers screwdriver. I soldered a new wire on to the pin and the old wire, then covered the splice with environmental heat shrink. Reassembled the connector, no more symptoms.

 

The interesting thing here is that the ECM did not set a code even though, the service manual says it should be set immediately on error. I would call this a bug in the ECM's software, but what can you do?

 

Thanks for your advice, catch you next time,

 

Athowhen.

[Olnick]

Way to go, Athowhen! All it takes is one teensy, hidden bad connection . . . and you found it! That's great to hear.

 

Happy motoring!