New Audi 4000 owner! Restoration thread
10-15-2018, 01:34 PM
#61
AudiWorld Member
Thread Starter
Yeah I was thinking..... Haha I didn't recognize any of those. You know, I haven't reset the ECU in a long time, should I do that? I'm gonna crank it today just to see what it does, wish me luck
10-15-2018, 04:33 PM
#62
AudiWorld Member
Thread Starter
Hey Y'all,
I had a huge paragraph typed out but I deleted it and I don't feel like retyping it right now, so here's the bullet points:
- Tested car again today. Fuel pump works great.
- The car has very consistent behavior: It takes 5-20 cranks to get to where it will idle without dying. After that it idles at about 900 rpm's. You can build up the engine speed by easing on the gas pedal, but the moment you open the secondary butterfly, it immediately chokes it down to near death while it sputters. Slamming the pedal to the floor at any point is an almost guarantee stall or drop to around 500 rpm. My main suspect right no is the CPA but I have no way to test it.
- There looks to be a missing relay under the dash? who knows what that could be. There are a collection of relays, three in total, with a blank space where one should be but isn't. Is this ECU related at all??
- When the engine idles, there is a whining noise coming from around the flywheel. As you increase rpm's the whine increases, and if you let off the gas it will subside briefly. The only way I could describe the sound is like the baby T-Rex from Jurassic Park: The Lost World. You know exactly what I'm talking about. I wonder if that's a hidden vacuum leak or what?
That dang CPA bothers me, anyone know where I could find on that isn't $250?
Let me know what you guys are thinking. Cheers
Rog, Let me know what you find out.
I had a huge paragraph typed out but I deleted it and I don't feel like retyping it right now, so here's the bullet points:
- Tested car again today. Fuel pump works great.
- The car has very consistent behavior: It takes 5-20 cranks to get to where it will idle without dying. After that it idles at about 900 rpm's. You can build up the engine speed by easing on the gas pedal, but the moment you open the secondary butterfly, it immediately chokes it down to near death while it sputters. Slamming the pedal to the floor at any point is an almost guarantee stall or drop to around 500 rpm. My main suspect right no is the CPA but I have no way to test it.
- There looks to be a missing relay under the dash? who knows what that could be. There are a collection of relays, three in total, with a blank space where one should be but isn't. Is this ECU related at all??
- When the engine idles, there is a whining noise coming from around the flywheel. As you increase rpm's the whine increases, and if you let off the gas it will subside briefly. The only way I could describe the sound is like the baby T-Rex from Jurassic Park: The Lost World. You know exactly what I'm talking about. I wonder if that's a hidden vacuum leak or what?
That dang CPA bothers me, anyone know where I could find on that isn't $250?
Let me know what you guys are thinking. Cheers
Rog, Let me know what you find out.
10-15-2018, 05:53 PM
#63
AudiWorld Junior Member
By the time the 4kq came along they no longer used a warm-up regulator (or control pressure regulator, CPR, as it's more often called in Bosch literature), although the block still had the spot where they used to go. Instead of that they moved to an electronic system stuck to the side of the fuel distributor. I prefer the CPR as it's a lot easier to deal with something mechanical I think.
The extra wires for the O2 sensor are to connect a meter to measure the AFR, basically. I understand you can use an analog multimeter (with a needle rather than an LCD display) to do this.
At any rate, you don't need to worry about that stuff. But it sounds like you're chasing phantom tails like me. I was sure the completely broken plug wires were the problem. Replaced them, still the same. That's how it goes. I think when one of us figures it out it'll be the same answer for the other.
I'm going to grab a new thermo time switch and see what that does. Mine is definitely temp related as well. I can't even drive it now that it's 90+ outside, it just runs too poorly. The part number is 0280130219 or you can get it from Autozone under the number SU5176. I'm not super convinced that they go bad easily, but they are fairly cheap.
Your coolant temp light could be a bad sensor in the coolant tank. I keep mine unplugged for the same reason.
-Rog
The extra wires for the O2 sensor are to connect a meter to measure the AFR, basically. I understand you can use an analog multimeter (with a needle rather than an LCD display) to do this.
At any rate, you don't need to worry about that stuff. But it sounds like you're chasing phantom tails like me. I was sure the completely broken plug wires were the problem. Replaced them, still the same. That's how it goes. I think when one of us figures it out it'll be the same answer for the other.
I'm going to grab a new thermo time switch and see what that does. Mine is definitely temp related as well. I can't even drive it now that it's 90+ outside, it just runs too poorly. The part number is 0280130219 or you can get it from Autozone under the number SU5176. I'm not super convinced that they go bad easily, but they are fairly cheap.
Your coolant temp light could be a bad sensor in the coolant tank. I keep mine unplugged for the same reason.
-Rog
Air idle valve or whatever the Audi community calls it, is worth another look. My W124 behaved the same as yours and almost drove me nuts until I found the issue. The burr I mentioned kept it in the open or closed position, giving crap responses and stalling. I see the Audi one has 3 connectors whereas Mercedes has only 2, so cant help you with which pin is which.
Another suggestion is to go up to your local store and grab an ol’ school vacuum gauge to help you pinpoint maybe what is wrong.
10-16-2018, 06:01 PM
#64
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Not sure if I can help, but here's a try..
If the current in the DPR isn't 'oscilating' a bit, that means the ECU is in 'open loop' mode, so not using the 02 sensor for an input, but just using the 'basic CIS' for fueling. Basically, using the CIS at whatever you adjusted it, without the ECU correcting anything.
Soo.. 'open loop' can be cause by O2 sensor being unplugged, full throttle switch being tripped, or ECU thinking motor is cold (so ignore's O2 sensor until warm).
Now you are also having troubles starting.. Knowing how often the coolant temp sensor fails, it may have failed to whre it thinks the motor is warm, making it really hared to start cold. Once the motor warms up a bit, runs better?
A quick test for that: When motor is dead cold: Unplug the connector to the coolant temp sensor (lower sensor on the head end of treh upper rad hose). The connector with the metal clip.
Then try to start. (If measuring the DPR current then, should go WAY up). If motor starts way better, then good chance the coolant temp sensor. IF not difference, maybe something else. (High resistance (or open circuit) to the temp sender makes ECU think motor is very cold)
And yes, see if you can find where that noise is coming from,as a big vacuum leak makes it a bugger to start. When cranking, almost *any* leak (that wouldn't matter when running), makes it hard to lift the CIS plate when craning. And if it doesn't lift, yon don't get fuel!
A good hose the check for a leak is the weird 'y' hose that has one end sort of heading to the idle air control, and is sort of on the motor side of the throttle. It sometimes collapses under vacuum, and gets a crack in it..
Looks like part '6A' in this diagram:
https://audi.7zap.com/en/usa/audi+co...-8/1/103-3010/
If the current in the DPR isn't 'oscilating' a bit, that means the ECU is in 'open loop' mode, so not using the 02 sensor for an input, but just using the 'basic CIS' for fueling. Basically, using the CIS at whatever you adjusted it, without the ECU correcting anything.
Soo.. 'open loop' can be cause by O2 sensor being unplugged, full throttle switch being tripped, or ECU thinking motor is cold (so ignore's O2 sensor until warm).
Now you are also having troubles starting.. Knowing how often the coolant temp sensor fails, it may have failed to whre it thinks the motor is warm, making it really hared to start cold. Once the motor warms up a bit, runs better?
A quick test for that: When motor is dead cold: Unplug the connector to the coolant temp sensor (lower sensor on the head end of treh upper rad hose). The connector with the metal clip.
Then try to start. (If measuring the DPR current then, should go WAY up). If motor starts way better, then good chance the coolant temp sensor. IF not difference, maybe something else. (High resistance (or open circuit) to the temp sender makes ECU think motor is very cold)
And yes, see if you can find where that noise is coming from,as a big vacuum leak makes it a bugger to start. When cranking, almost *any* leak (that wouldn't matter when running), makes it hard to lift the CIS plate when craning. And if it doesn't lift, yon don't get fuel!
A good hose the check for a leak is the weird 'y' hose that has one end sort of heading to the idle air control, and is sort of on the motor side of the throttle. It sometimes collapses under vacuum, and gets a crack in it..
Looks like part '6A' in this diagram:
https://audi.7zap.com/en/usa/audi+co...-8/1/103-3010/
Last edited by Katman; 10-17-2018 at 04:11 PM.
10-30-2018, 11:46 AM
#66
AudiWorld Member
Thread Starter
Hey guys,
So I cranked the car and it cranked well enough first try. I unplugged the temp sender plug and the engine idled rough for a bit but settled in to around 900 RPM's. While the engine was still cold, it would redline no problem at all. However, in a few minuted the engine warmed up and it ran terrible, so I plugged the sensor back up. It then died on me, but I got it cranked back up, and it ran alright at around 4000 RPM's limit. I think the problem might also be that temp sensor. I've ordered one and it wil come in this week. I'll update you on what happens with it.
Cheers
So I cranked the car and it cranked well enough first try. I unplugged the temp sender plug and the engine idled rough for a bit but settled in to around 900 RPM's. While the engine was still cold, it would redline no problem at all. However, in a few minuted the engine warmed up and it ran terrible, so I plugged the sensor back up. It then died on me, but I got it cranked back up, and it ran alright at around 4000 RPM's limit. I think the problem might also be that temp sensor. I've ordered one and it wil come in this week. I'll update you on what happens with it.
Cheers
10-30-2018, 09:57 PM
#67
AudiWorld Senior Member
Hey, me too. Mine is in the mail. Haven't gotten much time to work on my car. My battery relocation keeps dragging on. I keep meaning to look further into my idle switch as it looks to be missing something. Kind of wondering if it's one of the vacuum ones.
-Rog
-Rog
11-09-2018, 01:27 PM
#68
AudiWorld Member
Thread Starter
Hey Rog,
I got the temp sensor and WOW. The car has new life again. It ran great and I got the CO screw back in line. After that, I let the car sit for over a day. Then I walked back up to it and it fired right up, first crank! It idled great even cold, and had power to drive while cold. I took it down the road and pushed it pretty hard, and it did great, even after it got really warmed up! I can't believe it really is running so well. I tested it again today and sure enough, it cranked right up. I think I've finally beaten the motor problems! Ironically while I had it out driving, I got a flat tire. I just got a new set of Hankooks and threw them on, they make the car look great! I'm getting ready to drop the transmission so that I can figure out why third gear doesn't want to engage. Wish me luck. I hope the temp switch helps you out Rog!
I got the temp sensor and WOW. The car has new life again. It ran great and I got the CO screw back in line. After that, I let the car sit for over a day. Then I walked back up to it and it fired right up, first crank! It idled great even cold, and had power to drive while cold. I took it down the road and pushed it pretty hard, and it did great, even after it got really warmed up! I can't believe it really is running so well. I tested it again today and sure enough, it cranked right up. I think I've finally beaten the motor problems! Ironically while I had it out driving, I got a flat tire. I just got a new set of Hankooks and threw them on, they make the car look great! I'm getting ready to drop the transmission so that I can figure out why third gear doesn't want to engage. Wish me luck. I hope the temp switch helps you out Rog!
11-09-2018, 09:36 PM
#69
AudiWorld Senior Member
Nice! Yeah, I have both temp sensors now (making sure not to mix them up), so between that and being able to run all new grounds with my battery relocation, that ought to help a few things. I noticed when I was diagnosing that running a fat ground instead of that dinky stock one sure made the starter motor spin.
Glad to hear it's doing better.
-Rog
Glad to hear it's doing better.
-Rog
12-06-2018, 11:55 AM
#70
AudiWorld Member
Thread Starter
Hey all,
Well I've got the transmission of of the Quattro, it was an absolute pain. It's sitting out now, and I can tell third gear is not good. It wont go into third, even if the input shaft is still. It will go into fourth well. Could it be the syncro? Or the gear itself? I'm gonna tear it apart and see soon, is there a good place to find B2 tranny parts??
Cheers, Erik
Well I've got the transmission of of the Quattro, it was an absolute pain. It's sitting out now, and I can tell third gear is not good. It wont go into third, even if the input shaft is still. It will go into fourth well. Could it be the syncro? Or the gear itself? I'm gonna tear it apart and see soon, is there a good place to find B2 tranny parts??
Cheers, Erik