View Full Version : Bad CPS causing this?

11-04-2012, 05:49 AM
Running lean at idle (WB gauge pegged), pulled plugs and they are black, seems to correct itself (trying to) when I give it gas. But it will go back to bad idle and stalled on me once or twice so far at idle. Checked intake plumbing, swapped in my spare o2 sensor (same thing), and sort of stuck. Pulled codes...

P0113 (http://wiki.ross-tech.com/wiki/index.php/16497/P0113/000275) (IAT signal too high)
P1172 (Throttle body potentiometer sig 2 signal too low)
P1543 (http://wiki.ross-tech.com/wiki/index.php/17951/P1543/005443) (TB angle sensor, signal too small)
P1355 (http://wiki.ross-tech.com/wiki/index.php/17763/P1355) (Ignition circuit one open)
P1358 (http://wiki.ross-tech.com/wiki/index.php/17766/P1358) (Ignition circuit two open)
P1364 (http://wiki.ross-tech.com/wiki/index.php/17772/P1364) (Ignition circuit four open)
P1361 (http://wiki.ross-tech.com/wiki/index.php/17769/P1361) (Ignition circuit three open)
P1556 (http://wiki.ross-tech.com/wiki/index.php/17964/P1556/005462) (Charge pressure control: negative deviation)
P0341 (http://wiki.ross-tech.com/wiki/index.php/16725/P0341/000833) (Implausible signal from cam position sensor, and what I suspect is causing all the other crap to go haywire)
P1649 (http://wiki.ross-tech.com/wiki/index.php/18057/P1649/005705) (Power data bus: missing message from ABS controller. This code has been here ever since I got my tune, and I suspect that is the reason. never caused me an issue.)

Car: 2001 1.8T Quattro Manual Transmission (Quattro)
Mods: Built engine (forged rods/AEB pistons), GT2871R, Eurodyne tune, emissions written out, 3 bar FP ran on 630cc injectors, and other supporting mods. No 75 valve and written out of file.

Need some help here guys!

11-04-2012, 06:46 AM
I'd clear the codes and see what comes back. Sounds like you turned the key on with the coils, TPS, etc unplugged.

11-04-2012, 06:56 AM
Yeah, start out doing what Andrew said.

I've never seen a CPS randomly go bad, since it's just a hall sensor. Usually (98% of the time) if you get a code for your CPS, there is a wiring issue, or your cam timing is off.

11-04-2012, 07:02 AM
The codes are after I cleared them. Also disconnected the battery, ECU, and same symptoms. Did not scan for codes after I removed the battery and ECU. Also, the car seems to run fine for like the first 3 seconds, then it starts to act up.

11-04-2012, 07:03 AM
That's weird... might be a ground issue. How good is the coil pack ground?

11-04-2012, 07:10 AM
Coil pack ground is good. But one of the wires got burnt when my gasket blew, and exhaust gases basically went upwards (blew the top portion). Just checked and it is the one for cylinder 1 ignition coil. Ground is fine. Think that is the issue (the burnt wire)?

11-04-2012, 07:42 AM
i think its your cam position sensor. its just hall sensor. try pulling it off and cleaning it.

11-04-2012, 07:48 AM
I'll go do that right now. But upon new discovery, AFR is good when I give her gas. Kept her steady at 2k rpm and my AFR was 14.3:1 (shitty setting my car always ran at). As soon as I let off the gas and go into the lower rpm/idle, it goes to sh*t again. But going outside to clean the hall sensor to see how it pans out.

11-04-2012, 08:11 AM
Are you MAFless? Might be a small leak at the intake manifold somewhere.

14.3:1 while holding steady at 2k rpms is fine.

11-04-2012, 08:14 AM
Pretty sure I just put the CPS out of it's misery. Car won't even run now. It will turn over, but turn off right after. I used electrical parts cleaner on the contacts of the sensor and on the plug terminals. Anyways, looks like this part will def need to be replaced. What's with my bad luck? Beater out of commission due to valve body, hit a deer in my sister's Maxima, and now this. Mother is taking the day off tomorrow so I can use her car to get to school. Valve body is scheduled to come in Monday, so I will have the beater up and running (hopefully). And going to order the hall sensor for my vehicle in hopes it fixes my car. Just bad luck, I tell ya.

I am MAFless. My plumbing is the first thing I checked for. When the car was able to run (won't anymore), blow back from my BOV was also fully functional with the venting with revs .

11-04-2012, 08:34 AM
Your car will still run (but rough) with the CPS unplugged or removed.

I have tried it on my car and my brothers AEB B5..... so I think you're issue might be something else.

See if you can get someone to crank the car over, and check to see if you have spark. Just pull the Ignition Coil and you will hear it/see arc.

I dealt with a GTI that had almost this same exact thing happening. Turned out his intake cam somehow jumped 2 teeth retarded. No valve damage.

11-04-2012, 08:57 AM
The car will run with a bad cam sensor so thats not your issue. Do you have an adjustable fuel pressure regulator?

11-04-2012, 09:14 AM
Not an expert, but it seems more than just a coincidence that that the car won't run only after I removed the cam sensor and tried to clean it. And the car was running, so it def has spark. If you read one of my posts, I had my AFR steady when I kept revs above and steady at roughly 1500rpm (basically above idle). During that time, car felt perfectly right. No hiccups, rough engine, etc. But it stumbled when I let off the gas and drifted back into idle, and ran sh*tty again at idle. It was only at idle things went sour. But now, car will turn over and cuts off right after it does...only after I messed with the hall sender.

I also checked my fuel pressure. There are many things I checked, but did not post. My fuel pressure was dead on with ~43.5psi with vacuum line removed. I am getting fuel and spark, and combustion. Or was. But for now, I am going to order a new hall sender aka CPS aka cam position sensor. When that arrives, see how it goes.

I'm far from brushing off your guy's input, if it seems like that. It just seems that I need this thing replaced, by my diagnosis. But more feedback is more than welcome. I need my sh*t fixed, and this is what I am going to try to do to get it there. One of the many steps (maybe) till she is up and running again.

11-04-2012, 10:03 AM
How are you determining you have fuel and spark? Also your idle issue is due to those throttle body codes. I still think this is just a stupid fix like a loose ground wire. Don't have a wiring diagram with me but there's prob a common ground for all these connectors

11-04-2012, 10:06 AM
Did a little testing and analysis.

1) With hall sender unplugged car won't start (nice pop out the exhaust afterwards...lol)
2) With what I consider faulty hall sender placed in, car will turn over but die right after. This was the condition of the hall sender after I tried to clean it.
3) And then this thread started with the symptoms with me thinking it was the CPS, when it was not as bad as it is now. If the CPS is indeed the culprit.

New Bosch unit ordered and awaiting arrival.

How are you determining you have fuel and spark? Also your idle issue is due to those throttle body codes. I still think this is just a stupid fix like a loose ground wire. Don't have a wiring diagram with me but there's prob a common ground for all these connectors

Because the car was running. haha

11-04-2012, 10:18 AM
a pop out of the exhaust? Dude, check your timing, belt and cams. Please, before you do anything else.

11-04-2012, 10:23 AM
I assumed the pop was from me basically placing fuel into the chamber from me trying to turn her over, but no combustion.

I also had to edit my last post. Did not realize what I wrote down till now. But yeah, the 3 scenarios are correct now. I'll check my cam timing now. Update in a few min.

11-04-2012, 10:27 AM
If your timing is off, even by a tooth, combustion can happen while exhaust valves are open, possibly the "pop" you heard.

If you check your timing and everything is good, then the CPS could possibly be the problem.

11-04-2012, 11:50 AM
Timing is correct. Below are pics of the notches as close as I could get them without taking the bumper off to make room to get to the crank bolt. Basically removed fuel pump and had to keep playing with cranking. The notches are both right on the corner of the cap right by it. I am going on assumption my timing on the cam/crank gear are correct, because I'm really not in the mood to take my bumper off and move the front clip forward to confirm. I'll just take the me being able to rev the car with no issues and no valves hitting as a sign of good faith. Also been wanting to replace a couple wires on my harness anyways (injectors), so am about to source a replacement harness out.



11-04-2012, 06:31 PM
Also in the process of picking up engine harness to swap in (taking your guys advice, and a replacement harness seems the best solution if wiring is the case). Should be paying for it tomorrow hopefully and maybe even have time to have my car back to operation by the end of this coming weekend. Hopefully all parts will be here in a couple days.

11-04-2012, 07:41 PM
Also in the process of picking up engine harness to swap in (taking your guys advice, and a replacement harness seems the best solution if wiring is the case). Should be paying for it tomorrow hopefully and maybe even have time to have my car back to operation by the end of this coming weekend. Hopefully all parts will be here in a couple days.

Noone was suggesting the timing of the cams in relation to each other was off, rather that the belt slipped and the correlation of the cam sprocket to the crank sprocket is off. Sounds like you skipped time. I'd check that first.

11-04-2012, 07:59 PM
My timing is fine. Not being hard headed here (I know I am making myself look bad saying that), but I'm not going to go through the process of pulling my front clip forward just to confirm what I thought all along.

11-08-2012, 02:03 PM
Well, CPS did not fix the issue. And reason car would cut off immediately before was because I forgot to connect the damn TB connector back in after cleaning it [down]. Just noticed that in the engine bay today. Picked up an AWM engine harness and am going to swap it in tomorrow. But I have a question. There are 1-2 connectors on the replacement harness that are kind of fubered. Can you tell me the best route to swapping the plastic connector piece out without cutting the wires and soldering? Never did anything like this before. Thanks!

11-08-2012, 02:57 PM
Show me a pic of the connector. Your gonna wanna pull the pink locking tab out. Then they make special tools for different pins to push them out. You can try using a pick to p push down the looking tabs.

11-08-2012, 03:22 PM
I got the pins out of one of the fubered connectors. Found the little tab to push down and it came off. But since the plastic part the pins sit in were cracked, I just completed the job and broke the whole thing off. Pins are free, and one metal pin is damaged. I did not do this. It was like that, but I think some pressure with needle nose pliers can make it semi-clean again. But once I push it onto my old connector, I'm not really worried about getting it back out so it isn't a big deal.

Here are a couple pics. The connector intact is the one I just took apart (is actually a good one, but just a random one I just tried to see if I can take the pins out..n75). Then the 3 wires is the CPS connector (the irony) that was all cracked and sh*t. These are the only clear pics I could take.

good n75 connector semi-taken apart for experiemental purposes

pins already taken out of messed up connector


11-08-2012, 03:26 PM
Nice I gotta do the same thing for my coil pack connectors. Paid 67 for the four from my dealer what a ripoff haha

11-08-2012, 03:30 PM
Picked up the harness for $100 shipped. Not that bad of a deal, but I have seen better. But it was crunch time and this was the best deal I could find on a whim. Do you happen to have a pic of the tool I would need?

And I'm pretty sure it is the coil pack harness of the wiring that is causing my issue. When the gasket blew it threw a bunch of exhaust gases on that portion of my engine harness and the sheathing is cracked. Thought the wires would still be good inside, but I guess not. Well, that is what I'm hoping is the issue anyways. And taking the time to replace my injector portion of the harness with this job, because I've been wanting to do that for the longest time now.

11-08-2012, 03:51 PM
They are called terminal extraction tools they come in sets of like ten different tools

11-08-2012, 03:56 PM
Did a little Google searching and seen what it looks like. Seems I can just get the little circular one with a whole bunch of different types attached. About to run to Radio Shack to pick one up. They should have it. Been trying for like the last 10 min with a small electricians screwdriver to no avail. Tried a paper clip also. Seems I need the proper tool.

11-08-2012, 06:27 PM
Went to Radio Shack, Autozone, Sears, Home Depot, Lowes, and the dreaded Walmart. None of these places had it. Cwme home and fiddled with it a little more and mastered it in like 5 min (not really, but you get the idea). Little electrician's flat-head screwdriver is all you really need. Just took me a while to figure out that sweet spot. Soon as I found it on one terminal, took the other one out in like 20 seconds.

11-09-2012, 01:57 PM
Swapping engine harness is a PIA. Anyways, just about donme with swapping it out. Had to play with the harness to make it complete. 3 connectors swap (1 terminal exchange, one wire on the new harness was simply missing a connector, and the oil pressure wire had some home rigged connector on it). This harness is not all that great, but the wires that are important seem to be intact.

But I have yet another question. Leaning on my TB cover, I snapped a small piece of plastic off and it is sitting on top of my crank gear now. Do you guys know of some type of trick to get it out? Something like the bubble gum on the end of a stock trick? Thanks!

11-09-2012, 04:33 PM
Long screw driver with dumb dumb on it. Bbubble gum mightml work just chew it so it's sticky. Id try to find dumb dumb though

11-09-2012, 04:39 PM
What's dumb dumb?

11-09-2012, 07:11 PM
Sorry dum Dum, it's a soft sticky thing. Works great on the end of sockets to keep bolts from falling out. Can use 3m strip caulk. Will be exactly what you need. You should get a roll amid keep it around. Once you use it you will see how versatile it is

11-10-2012, 10:55 AM
Dude sold me a funky wiring harness. Need to pick up another one and go from there. Plus need to get my money back for this garbage. And found where the wiring issue was on my original harness. It was def a wiring issue.

11-10-2012, 11:46 AM
Nice job finding the problem

11-15-2012, 03:25 PM
Can I get a f*cking break?

Replacement harness is in, and I did not know the little differences between the Passat (assuming where this came from) and A4. Coolant tank connector is different (no biggie. just going to swap it out) and it has no reverse switch harness. Then there are extra connectors I have no idea what they are there for.

But on other news, ECU may have an issue. Leaving in a couple min to send it off to my tuner with a spare included. Check engine light is on cluster when in starting position and fuel pump prime. But I have no spark. Did this with the last engine harness, and I blamed it on the harness. But it is doing it on this harness too, so not quite sure what's up. No TB prime and no spark. Just going to have Arnold (my tuner) look at the ECU to see if he can spot anything. If not, he will need to send it to CTapp and have them check out the ECU. If they deem it faulty, he will get credit to retune my spare ECU and he sends that back. Well, I think that is how it goes. Not sure if there are any fees associated with this or not, other than shipping. Hope not.