HELP!? - Intermittent Engine Stalling During Warm-Up
Posted: April 29th, 2006, 10:13 pm
Okay, my girlfriend has a 1992 Mazda MX3 GS w/1.8 V6 5 speed.
Last fall it crapped out in her mom's driveway. A family friend/GM Mechanic took a look and diagnosed it as distributor, replaced it, and several hundred dollars later her car ran well.
That is, until the crazy idle problems began. Surging idle and inconsistant stalling. This was fixed after the mech found a leak in the intake tubing from the airbox to the IAC/TB. This was removed, siliconed, and replaced. No holes, no idle problems.
Again, that is, until... About a month or two ago it started surging oddly and dying on her at random. Since I was not present I can't say exactly what it did for her. I was with her when it did it once. It died as she came to a stop at an intersection. She started panicking, so I switched seats with her, tried to get it to run, to no immediate luck. The car would turn over fine but refused to start. I sat in it a few minutes and finally got it going, turned into a nearby parking spot and drove home.
Thinking this was might be vacuum/intake hose related, I again removed the intake hose and made double sure there were no holes. She drove it to a nearby town the next day, apparently it died on the road up there, but she coasted into a Mazda dealership where they diagnosed her problem as being her distributor.
The GM Mechanic found the paperwork and replaced the distributor under warranty(thank god). The car was still warm when we picked it up, we drove it home and it was fine all the way, or so it seemed.
The next day, after it had cooled down, the car decided it didn't like the idea of running. It would start, idle high (normal for this cool weather), and then without apparent reason, cut out, or erratically start to surge and then die. Sometimes, with some aggressive pumping of the throttle it would catch and pickup, but I had to hold it at around 3000 rpm to keep it from dying on me. Every so often, under consistant pedal pressure, the revs would dip 100-200 rpm. Then, once it was warm, the problem seemed to go away.
Again, the mechanic looked at it, stumped and nearly as displeased as me, (but not nearly as displeased as my gf, who insisted I couldn't be as upset as her since it wasn't my car) and started wiggling things around, trying to find a bad electrical connection or leaky vacuum valve. He pushed on the airbox a few times and the engine seemed do come close to dying each time, which led us to check the electrical connections on the VAF.
Driving later that night, it died, while in gear. Tachometer went straight to 0 even though the car was still in motion in third gear. I heard a click, just as suddenly as they'd dropped, the revs caught up and the car ran for a few seconds before I heard another click. No power again, and the tach needle at 0. Click. Running. The car got me to the grocery store. I went in, did my thing, drove home. No further problems that night.
I pulled the entire airbox out, checked all electrical connections in the area, made sure there was nothing grounding, replaced the airbox, ensured there were no vacuum leaks, and drove 30 km with no problems.
I was late for work the next morning after my girlfriend offered me a ride to work. The car started, idled for about 30 seconds, and died. I jumped in, same thing happened. The car suffered a slammed door.
The dying now only occurred during warm up.
One of the teachers at the local college who also works part time at Canadian Tire (where I work) looked at it yesterday, and after an hour of scoping and diagnostics, didn't have much of an answer. Everything seemed good. Then again, the car was running and warm.
What he did find though, which may have explained some of the car's issues, and in fact some issues that other MX3 owners on this site have been having, was that there was a coolant leak just below the rad cap housing. The coolant was dripping down onto the electrical connector for the Cam Angle Sensor. Looking at the wiring schematics, we decided the coolant could be shorting the wires and modifying the signal to the ECU, resulting in it killing the engine.
I let the car cool, removed the rad cap, removed the rad cap housing, ignored the O-ring that was supposed to seal the housing to the pipe, cut a gasket, applied sealant to both sides and put the housing back on, topped up the coolant, and stuck a new shiny "bling" blue rad cap on there to prevent any other forms of leaks, and to make sure my coolant system had propper pressure. Then I tackled the wiring harness with contact cleaner, reconnected it, and stood back as the evening parts staff marvelled at the rad cap, insisting I should have an increase of at least 40 hp because of its 'bling' factor.
I started the engine, waited for it to warm up. Waited for it to die. Nothing. No dying. 'What the hell? This isn't very Prissy Die-er like. What's going on?' I wondered.
Truth be told, I took it out for a road test and it worked better than it has for months. Seemed to have more power, idled better. I was loving it. I brought it back to town, let my gf drive it, and she agreed that it was running better. I warned her not to get too excited, as this may not be the total problem.
So this morning I started it up, it started up perfectly. Idled smooth. No hunting like it used to have. Once the temperature guage got just over the bottom line it stalled out. No apparent reason, no dip in revs to warn me. Just. Dead.
I got back in, restarted it, with a bit of trouble, it tried to die, caught itself, then died again.
I'm a persistant bugger. I got back in, started it, didn't try to aid it, and it continued to run fine. The temp gauge got up to high-center where it usually sits and the car ran fine all around town since then.
So... I'm thinking the next step is EGR cleaning or TPS adjustment. Any comments?
Also: While I understand that when you put the car in gear at idle, the revs go up a couple hundred rpms, which it is doing fine when it's warm right now. The only other thing is, when I apply the brakes IN THIS SITUATION ONLY, the car idle hunts. The revs play up and down consistantly with a difference of about 800 rpm. If I remove my foot from the brake, this condition stops. If I put the car in neutral and hit the brakes, there is the slightest dip in revs, but no surging. I also noticed that, when the car is in gear with the clutch depressed, if I pull the e-brake, I hear a relay click as the brake warning indicator lights on the dash, and click again when the light turns off as I put the ebrake handle back down. This is followed immediately by a dip of 100 or so in the revs. Again, this is only while the clutch is engaged and the car is in gear. Somebody who knows more about the circuitry in this car may be able to help here? I know that the relay or switch that I'm hearing clicking is in the same location as the A/C Relay should be. The car doesn't have A/C, though I'm not sure if that matters.
Please, any help would be greatly appreciated. I've sorted through the archives and searched everywhere, but I'm running out of ideas. Thank you!
Last fall it crapped out in her mom's driveway. A family friend/GM Mechanic took a look and diagnosed it as distributor, replaced it, and several hundred dollars later her car ran well.
That is, until the crazy idle problems began. Surging idle and inconsistant stalling. This was fixed after the mech found a leak in the intake tubing from the airbox to the IAC/TB. This was removed, siliconed, and replaced. No holes, no idle problems.
Again, that is, until... About a month or two ago it started surging oddly and dying on her at random. Since I was not present I can't say exactly what it did for her. I was with her when it did it once. It died as she came to a stop at an intersection. She started panicking, so I switched seats with her, tried to get it to run, to no immediate luck. The car would turn over fine but refused to start. I sat in it a few minutes and finally got it going, turned into a nearby parking spot and drove home.
Thinking this was might be vacuum/intake hose related, I again removed the intake hose and made double sure there were no holes. She drove it to a nearby town the next day, apparently it died on the road up there, but she coasted into a Mazda dealership where they diagnosed her problem as being her distributor.
The GM Mechanic found the paperwork and replaced the distributor under warranty(thank god). The car was still warm when we picked it up, we drove it home and it was fine all the way, or so it seemed.
The next day, after it had cooled down, the car decided it didn't like the idea of running. It would start, idle high (normal for this cool weather), and then without apparent reason, cut out, or erratically start to surge and then die. Sometimes, with some aggressive pumping of the throttle it would catch and pickup, but I had to hold it at around 3000 rpm to keep it from dying on me. Every so often, under consistant pedal pressure, the revs would dip 100-200 rpm. Then, once it was warm, the problem seemed to go away.
Again, the mechanic looked at it, stumped and nearly as displeased as me, (but not nearly as displeased as my gf, who insisted I couldn't be as upset as her since it wasn't my car) and started wiggling things around, trying to find a bad electrical connection or leaky vacuum valve. He pushed on the airbox a few times and the engine seemed do come close to dying each time, which led us to check the electrical connections on the VAF.
Driving later that night, it died, while in gear. Tachometer went straight to 0 even though the car was still in motion in third gear. I heard a click, just as suddenly as they'd dropped, the revs caught up and the car ran for a few seconds before I heard another click. No power again, and the tach needle at 0. Click. Running. The car got me to the grocery store. I went in, did my thing, drove home. No further problems that night.
I pulled the entire airbox out, checked all electrical connections in the area, made sure there was nothing grounding, replaced the airbox, ensured there were no vacuum leaks, and drove 30 km with no problems.
I was late for work the next morning after my girlfriend offered me a ride to work. The car started, idled for about 30 seconds, and died. I jumped in, same thing happened. The car suffered a slammed door.
The dying now only occurred during warm up.
One of the teachers at the local college who also works part time at Canadian Tire (where I work) looked at it yesterday, and after an hour of scoping and diagnostics, didn't have much of an answer. Everything seemed good. Then again, the car was running and warm.
What he did find though, which may have explained some of the car's issues, and in fact some issues that other MX3 owners on this site have been having, was that there was a coolant leak just below the rad cap housing. The coolant was dripping down onto the electrical connector for the Cam Angle Sensor. Looking at the wiring schematics, we decided the coolant could be shorting the wires and modifying the signal to the ECU, resulting in it killing the engine.
I let the car cool, removed the rad cap, removed the rad cap housing, ignored the O-ring that was supposed to seal the housing to the pipe, cut a gasket, applied sealant to both sides and put the housing back on, topped up the coolant, and stuck a new shiny "bling" blue rad cap on there to prevent any other forms of leaks, and to make sure my coolant system had propper pressure. Then I tackled the wiring harness with contact cleaner, reconnected it, and stood back as the evening parts staff marvelled at the rad cap, insisting I should have an increase of at least 40 hp because of its 'bling' factor.
I started the engine, waited for it to warm up. Waited for it to die. Nothing. No dying. 'What the hell? This isn't very Prissy Die-er like. What's going on?' I wondered.
Truth be told, I took it out for a road test and it worked better than it has for months. Seemed to have more power, idled better. I was loving it. I brought it back to town, let my gf drive it, and she agreed that it was running better. I warned her not to get too excited, as this may not be the total problem.
So this morning I started it up, it started up perfectly. Idled smooth. No hunting like it used to have. Once the temperature guage got just over the bottom line it stalled out. No apparent reason, no dip in revs to warn me. Just. Dead.
I got back in, restarted it, with a bit of trouble, it tried to die, caught itself, then died again.
I'm a persistant bugger. I got back in, started it, didn't try to aid it, and it continued to run fine. The temp gauge got up to high-center where it usually sits and the car ran fine all around town since then.
So... I'm thinking the next step is EGR cleaning or TPS adjustment. Any comments?
Also: While I understand that when you put the car in gear at idle, the revs go up a couple hundred rpms, which it is doing fine when it's warm right now. The only other thing is, when I apply the brakes IN THIS SITUATION ONLY, the car idle hunts. The revs play up and down consistantly with a difference of about 800 rpm. If I remove my foot from the brake, this condition stops. If I put the car in neutral and hit the brakes, there is the slightest dip in revs, but no surging. I also noticed that, when the car is in gear with the clutch depressed, if I pull the e-brake, I hear a relay click as the brake warning indicator lights on the dash, and click again when the light turns off as I put the ebrake handle back down. This is followed immediately by a dip of 100 or so in the revs. Again, this is only while the clutch is engaged and the car is in gear. Somebody who knows more about the circuitry in this car may be able to help here? I know that the relay or switch that I'm hearing clicking is in the same location as the A/C Relay should be. The car doesn't have A/C, though I'm not sure if that matters.
Please, any help would be greatly appreciated. I've sorted through the archives and searched everywhere, but I'm running out of ideas. Thank you!