88 S4 has started running like a poorly tuned lawn mower
#46
Drifting
Thread Starter
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Ok, more troubleshooting done.
Checked MAF and TEMP II wiring, both looked good. Taped them back up and plugged them back in.
Checked LH ground on driver's side of block, under FPR. It is tight and cable looks good.
Checked grounds at top of central fuse panel, all tight.
Checked resistance between MAF 4 and LH 5 and between MAF 2 and LH 6, both registered .8
Started the car and it started up immediately and idled steady, no hunting whatsover. Idling a little high, at 1k, but a solid idle. Took it for a quick spin around the block. No hesitations, or erratic idle.
Next step was to unplug Temp II and battery and O2 as John suggested, after getting it warmed up. I put the air filter back on and buttoned everything up and started the car. Horrible idle. Thinking I might not have the MAF plugged in tightly, I popped the hood with the car running and went to get at the MAF. When I pulled the air filter, the car surged a bit and settled on a stead idle. Weird! I set the air filter back down and the car bogged down, I removed it and the car perked right back up. The air filter isn't super old, but I guess it's restrictive. I have another one already on the way, so I will test this with the new filter tomorrow.
I went ahead and unplugged the Temp II and battery and then O2 and plugged the battery back in. No real improvement in how it's running. One thing I notice is that after a rev, when it's returning to idle, it dips a little low and goes a little high and then settles on a steady idle. It will rev steadily and strongly, no hesitations or misses. It's not running great, though, like I think it should with new plugs, injectors, LH, etc.
It is still running super rich though, exhaust smells awful and it burns my eyes and nose.
So, did any of that turn on any light bulbs for anyone or at least eliminate something so I can continue checking elsewhere.
I am picking up a new FPR tomorrow as well.
Checked MAF and TEMP II wiring, both looked good. Taped them back up and plugged them back in.
Checked LH ground on driver's side of block, under FPR. It is tight and cable looks good.
Checked grounds at top of central fuse panel, all tight.
Checked resistance between MAF 4 and LH 5 and between MAF 2 and LH 6, both registered .8
Started the car and it started up immediately and idled steady, no hunting whatsover. Idling a little high, at 1k, but a solid idle. Took it for a quick spin around the block. No hesitations, or erratic idle.
Next step was to unplug Temp II and battery and O2 as John suggested, after getting it warmed up. I put the air filter back on and buttoned everything up and started the car. Horrible idle. Thinking I might not have the MAF plugged in tightly, I popped the hood with the car running and went to get at the MAF. When I pulled the air filter, the car surged a bit and settled on a stead idle. Weird! I set the air filter back down and the car bogged down, I removed it and the car perked right back up. The air filter isn't super old, but I guess it's restrictive. I have another one already on the way, so I will test this with the new filter tomorrow.
I went ahead and unplugged the Temp II and battery and then O2 and plugged the battery back in. No real improvement in how it's running. One thing I notice is that after a rev, when it's returning to idle, it dips a little low and goes a little high and then settles on a steady idle. It will rev steadily and strongly, no hesitations or misses. It's not running great, though, like I think it should with new plugs, injectors, LH, etc.
It is still running super rich though, exhaust smells awful and it burns my eyes and nose.
So, did any of that turn on any light bulbs for anyone or at least eliminate something so I can continue checking elsewhere.
I am picking up a new FPR tomorrow as well.
#47
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Sounds more like a bad MAF to me. Do you happen to have a good one close to you that you can try out?
#48
Drifting
Thread Starter
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I have my original MAF and a used one I picked up. I will swap my old one back in and see if there is a difference. I do plan to get one of the MAFs rebuilt as soon as my slush fund starts filling back up.
I'll try to contact the locals and see if there is a MAF to borrow.
I'll try to contact the locals and see if there is a MAF to borrow.
#50
Drifting
Thread Starter
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Today's update.
The first thing I wanted to do was test fuel pressure. I borrowed a fuel pressure tester from Autozone on my way home.
Went to back the car out of the garage to work on it in the driveway, car would crank but would not start at all until I plugged the Temp II sensor back in. It and the O2 were unplugged and the battery unhooked and hooked back up last night at John S's suggestion.
One I plugged the Temp II back in, the car fired up immediately and hit a steady 800 idle, no hunting at all. I unplugged the Temp II as it ran and the idle would get a little choppy and settle down when I plugged it back in.
The pressure tester I borrowed would not thread onto the fuel rail end as they promised, so no fuel pressure test today. I took the car out to get it warmed up to see if anything changed. I noticed that after a few hard accelerations and revs, it has stopped belching black smoke. Unlike yesterday, when I decelerated with the clutch in, the RPM's would not bottom out and bounce around before settling, they would drop down to 800 or so and stay there.
After it got warm, it changed a bit, still not running rich but when I pushed the clutch in and let the RPM's drop, it would drop down to 600 and then settle back up at 800. The idle did seem to hunt a bit as I sat at stop lights, 750 to 800 range.
I do not have the air filter or housing on yet, so the MAF might not like the weird air pattern its getting, but I don't think that would be much of an issue at a stop light.
Should I plug the O2 sensor back in and see what happens? Do I need to reset the battery after plugging the O2 back in?
Also, I thought the injectors might be stuck on all the time, which would certainly over fuel. With ignition on, they are not clicking. Do I need to do something else to rule that out?
Tomorrow I will get another fuel pressure tester. I also plan on checking each plug wire for proper spark, test compression, and test voltage on each injector.
My FPR did not come in yet. I was hoping to swap that out tonight too. Maybe tomorrow.
The first thing I wanted to do was test fuel pressure. I borrowed a fuel pressure tester from Autozone on my way home.
Went to back the car out of the garage to work on it in the driveway, car would crank but would not start at all until I plugged the Temp II sensor back in. It and the O2 were unplugged and the battery unhooked and hooked back up last night at John S's suggestion.
One I plugged the Temp II back in, the car fired up immediately and hit a steady 800 idle, no hunting at all. I unplugged the Temp II as it ran and the idle would get a little choppy and settle down when I plugged it back in.
The pressure tester I borrowed would not thread onto the fuel rail end as they promised, so no fuel pressure test today. I took the car out to get it warmed up to see if anything changed. I noticed that after a few hard accelerations and revs, it has stopped belching black smoke. Unlike yesterday, when I decelerated with the clutch in, the RPM's would not bottom out and bounce around before settling, they would drop down to 800 or so and stay there.
After it got warm, it changed a bit, still not running rich but when I pushed the clutch in and let the RPM's drop, it would drop down to 600 and then settle back up at 800. The idle did seem to hunt a bit as I sat at stop lights, 750 to 800 range.
I do not have the air filter or housing on yet, so the MAF might not like the weird air pattern its getting, but I don't think that would be much of an issue at a stop light.
Should I plug the O2 sensor back in and see what happens? Do I need to reset the battery after plugging the O2 back in?
Also, I thought the injectors might be stuck on all the time, which would certainly over fuel. With ignition on, they are not clicking. Do I need to do something else to rule that out?
Tomorrow I will get another fuel pressure tester. I also plan on checking each plug wire for proper spark, test compression, and test voltage on each injector.
My FPR did not come in yet. I was hoping to swap that out tonight too. Maybe tomorrow.
#51
Team Owner
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if you have not already done so put in a fresh MAF,
not an old one,
send one of the ones you have out for a rebuild and make that the next step,
dont do anything else till you do a fresh MAF swap
not an old one,
send one of the ones you have out for a rebuild and make that the next step,
dont do anything else till you do a fresh MAF swap
#53
Team Owner
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I think that what i am saying is dont keep on looking for things that are not broken till you do the MAF,
right now it sounds like you chasing you tail and you will eventually damage something else thats not the reason your having running issues.BTDT
right now it sounds like you chasing you tail and you will eventually damage something else thats not the reason your having running issues.BTDT
#55
Rennlist Member
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Leave the O2 sensor disconnected, and put the airfilter back on. Leave Temp 2 connected.
I did say previously to only disconnect Temp2 for fault finding when engine was warm, as when it is disconnected the Warmup map is defaulted to 80degC condition (so car won't want tro start from cold)
Let us know what you find. It would be unlikely that 2 MAFs would be similarly faulty....
I did say previously to only disconnect Temp2 for fault finding when engine was warm, as when it is disconnected the Warmup map is defaulted to 80degC condition (so car won't want tro start from cold)
Let us know what you find. It would be unlikely that 2 MAFs would be similarly faulty....
#56
Rennlist Member
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You might also change the air filter. It sounds to me like yours is full enough of something as to restrict the air flow. Jerry Feather
#57
Drifting
Thread Starter
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Yes, new filter going on today.
Car is running pretty good today, idle is still a little erratic and if i push the clutch in and rev high, the RPMs will usually bottom out and kill the car. Pushing the clutch in from a normal acceleration causes the idle to return to about 600, pop up to 1k and settle quickly on 800. I'll be sending my spare MAF off for a rebuild in a couple weeks, so hopefully this is the last piece.
Upon returning from my drive around this morning, there was some steam coming from under the hood, near the windshield/cowl area. I opened the hood and pulled the cowl cover off and it seemed to be coming from the heater box area. I also noticed the inside windshield steaming up pretty heavily. It was raining and the windows were up, so they were steaming up anyway, but it seemed to be a bit excessive. I am losing a bit of coolant too, the coolant level warning comes on every 3 or 4 days. Head gasket?
Car is running pretty good today, idle is still a little erratic and if i push the clutch in and rev high, the RPMs will usually bottom out and kill the car. Pushing the clutch in from a normal acceleration causes the idle to return to about 600, pop up to 1k and settle quickly on 800. I'll be sending my spare MAF off for a rebuild in a couple weeks, so hopefully this is the last piece.
Upon returning from my drive around this morning, there was some steam coming from under the hood, near the windshield/cowl area. I opened the hood and pulled the cowl cover off and it seemed to be coming from the heater box area. I also noticed the inside windshield steaming up pretty heavily. It was raining and the windows were up, so they were steaming up anyway, but it seemed to be a bit excessive. I am losing a bit of coolant too, the coolant level warning comes on every 3 or 4 days. Head gasket?
#58
Team Owner
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check the heater hose connections under the expansion valve
#59
Drifting
Thread Starter
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The heater hose at the heater valve is what it was. The 2nd time I've replaced this. I gave the upper radiator hose a squeeze and coolant shot straight up out the that short piece between the block and the heater valve. Easy fix, glad this one was simple and cheap.
#60
Drifting
Thread Starter
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I thought I'd get the car smog tested again after the new ECU, plugs, etc, just to see where I'm at.
Before this work, I failed the test with high CO. 7.26 with an allowed limit of 1.2. My HC was 196 and CO2 was 9.71.
I've been running 93 octane shell gas for a week or so. I ran it hard on the interstate on the way to the test station.
Now, with the O2 still unplugged and a used MAF, the car is running reasonably well, doesn't smell rich at all. I have the cats back on, but no air injection installed.
The car failed ever worse.
CO went up, 9.34, HC went up, 681, but CO2 went down, 8.04.
A while back, I advanced the timing with Porken's timing tool. Would that contribute to the emission results above? What else could be contributing? The MAF probably isn't working well, but it will be a couple of weeks before I can have my spare rebuilt. I'll have to buy clutch parts before that.
Any tips or tricks to pass?
Before this work, I failed the test with high CO. 7.26 with an allowed limit of 1.2. My HC was 196 and CO2 was 9.71.
I've been running 93 octane shell gas for a week or so. I ran it hard on the interstate on the way to the test station.
Now, with the O2 still unplugged and a used MAF, the car is running reasonably well, doesn't smell rich at all. I have the cats back on, but no air injection installed.
The car failed ever worse.
CO went up, 9.34, HC went up, 681, but CO2 went down, 8.04.
A while back, I advanced the timing with Porken's timing tool. Would that contribute to the emission results above? What else could be contributing? The MAF probably isn't working well, but it will be a couple of weeks before I can have my spare rebuilt. I'll have to buy clutch parts before that.
Any tips or tricks to pass?