# Please HELP - P0321 Ignition/Distributor Engine Speed Input Circuit



## Mesix (Jun 8, 2009)

I own a 2001 Audi TT 225 quattro. I have recently had my motor rebuilt. Ever since the rebuild it has been difficult to start, and I get a check engine light at about 3,500 RPM. The engine code I get is: 

P0321 Ignition/Distributor Engine Speed Input Circuit. 

I have read about common causes for this code. Both the crank and cam sensors have been replaced. The battery has been replaced. The starter has not been replaced, but seems to be functioning normally (tries to start even though it won't turnover). Timing seems to be okay. Engine runs fine if it starts (seldom), and hesitates momentarily at about 3,500 RPM when the light comes on, but will rev through the full range smoothly otherwise. 

Outside of the common causes, can any of these changes done during the rebuild be a contributing cause? 

Spec Stage 3+ Clutch and 14 lb flywheel 
Displacement increased to 2008 cc (83 mm bore 92.8 mm stroke) 
Cat Cams (3651) in AEB head 

Should I assume that the difficulty starting and the engine code are related, or are they likely to be separate problems?


----------



## Mesix (Jun 8, 2009)

Regarding the code, is it possible that the light weight flywheel is causing this problem? The engine is revving faster than the computer expects and this code may be indicative of the faster revving.


----------



## AmIdYfReAk (Nov 8, 2006)

This'll help you out. 

http://wiki.ross-tech.com/wiki/index.php/16705/P0321/000801


----------



## Charlie_M (Mar 23, 2011)

I guess you have the AMU motor? It may be something simple, like the electrical interference (EMI) referred to in the TSBs linked to in above post. When you say 'engine runs OK if it starts', do you mean that it *drives* OK (with power) or that it just *revs* OK? 

Sounds like a timing issue to me; I know you said 'timing seems OK', but what do you mean? Ignition timing? TB tooth indexing? TB sprocket adjustment? CAM Timing chain? 

Are you sure your builder degree'd the cams? Do you have an adjustable TB cam sprocket? 

Also have you read the info from FAQ about using AEB heads on later motors: 

Head Swapping - Large Port/AEB head on Small Port Block and the reverse 
All 20v heads are interchangeable! 

* Large port heads have no provision for the combi valve, thus you're secondary air injection pump not properly functioning and will throw a CEL. CELs can be avoided with resistors or better yet some chip tuner's code will ignore the errors and not display the CEL. 
* On engines with VVT you can swap the VVT solenoid into a non-VVT head without issue. 
* AEBs use 1 window cam trigger wheels, if your putting the AEB head on a small port post 2000 motor be sure to use the 4 window trigger wheel from the original head 
* Cam pulley must match the short block. Putting a large port AEB head on a post 2000 06A block must retain the OE cam pulley, the 058/AEB pulley will not seat the timing belt correctly.​


----------



## Mesix (Jun 8, 2009)

Thanks for the advice. I'll give a little more info in response to your questions. 

The car does not start when I turn the key. I can hear the rrrrr noise of the starter trying to start the engine, but it rarely starts. If the car is pushed (or towed) and started with the clutch/transmission when rolling, it will start every time. Once it is running, the engine sounds great and runs really well. 

When the car hits about 3,500 RPM, the engine light comes on and there is a slight hesitation. At first, I was wary of taking it over 3,500 RPM, but after some experimentation I discovered that the engine runs fine at higher RPM as well after it gets over the 3,500 RPM hump. It is when this slight hesitation occurs that the engine code P0321 appears in the computer. If I clear the code and start the car again, the check engine light will be out and the code will not appear unless the engine reaches the 3,500 RPM range. 

The timing seems to be okay since the markings on the cams line up properly. The cam trigger wheel is the right one for my 1.8t. The timing belt is seated properly, so I assume it is the right cam pulley. Arnold from Pag Parts built the head for me so it is not just a used head swapped onto my motor. The engine also runs very well (except for the above mentioned hesitation and engine light/code). 

I'm starting to wonder if the starter motor might need to be replaced. That might fix the starting problem, but I assume the code would still be present, which would prevent me from registering the car since it will fail inspection.


----------



## Charlie_M (Mar 23, 2011)

Sounds like a crank position sensor problem. I did some searching, and found another post that also described very hard starting and a stumble & CEL, but at 3200 RPM. That guy solved it with a new CPS, but you say you've already done that. 

* Check the crankshaft position sensor wiring (connector and wiring harness to ECU)? 
* Any teeth missing on the CPS 'reluctor' (toothed disk inside the motor)? 
* Any way for the 'reluctor' to be not centered on the crank? (IE, have some run-out) 
* Sure the CPS is the right P/N for the ECU? OEM or Chinese? 
* Ohm CPS sensor pins? 
* Ohm CPS sensor leads at ECU harness? 
* Look at VW TSBs that refer to additional grounding for the CPS on some motors? 

Edit: Looked up CPS resistance specs (2001 AMU): 
Pin 1 = shielding (at square, keyed end of harness connector) = ECU 108 
Pin 2 = ground = ECU 90 
Pin 3 = signal = ECU 82 

On the sensor, pins 2-3 should read 730-1000 ohms, while pins 1-3 and pins 1-2 should read infinite ohms (no connection) 

If that's OK, unplug ECU connector, and check from ECU pins to CPS harness. Check for continuity, shorts to ground and shorts to power.


----------



## Charlie_M (Mar 23, 2011)

Mesix said:


> I'm starting to wonder if the starter motor might need to be replaced. That might fix the starting problem, but I assume the code would still be present, which would prevent me from registering the car since it will fail inspection.


 I'm pretty sure it's not your starter, or the motor reving too fast from the lightweight flywheel. Try CPS diagnostics I wrote above. 

Do you have another ECU you could try, if those tests above all work out?


----------



## Mesix (Jun 8, 2009)

Thanks, I'll have a look at that tomorrow when I get a chance to get down to the garage again. 

One concern that I have is that the 2008 cc stroker kit required the crank to be replaced with a crank from the 2.0 FSI motor. The crank was machined and balanced along with the lighter fly wheel. I used the OEM crank position sensor from the 1.8t motor. Could the different crank be the cause of the code? 

...and no I don't have another ECU, but I could probably get one easy enough. I've been weighing the option of getting a later year "wideband" ECU to replace mine when I upgrade the turbo. The first priority is to get this beast up and running though before I throw any more money at nonstandard parts.


----------



## Charlie_M (Mar 23, 2011)

Mesix said:


> One concern that I have is that the 2008 cc stroker kit required the crank to be replaced with a crank from the 2.0 FSI motor. The crank was machined and balanced along with the lighter fly wheel. I used the OEM crank position sensor from the 1.8t motor. Could the different crank be the cause of the code?


 No, I don't think so, unless the impulse wheel is bent somehow. I'm pretty sure the only change needed for a 2.0 FSI crank is to put on the right oil pump gear for the 1.8T.


----------



## Mindfault (Feb 2, 2010)

Subscribed to remembaa


----------



## groggory (Apr 21, 2003)

Charlie_M said:


> Sounds like a crank position sensor problem. I did some searching, and found another post that also described very hard starting and a stumble & CEL, but at 3200 RPM. That guy solved it with a new CPS, but you say you've already done that.
> 
> * Check the crankshaft position sensor wiring (connector and wiring harness to ECU)?
> * Any teeth missing on the CPS 'reluctor' (toothed disk inside the motor)?
> ...


 Added this to the FAQ


----------



## Mesix (Jun 8, 2009)

Thanks for all the information. Tomorrow we are going to drop the oil pan to inspect the crankshaft and impulse wheel. After that we might replace the aftermarket cams with OEM cams to rule that out. After that I am out of ideas and may have to part this project motor out and just put a used stock motor back in.


----------



## Mesix (Jun 8, 2009)

Well, we've tried just about everything. I'd really hate to have to take the motor out of the car after putting so much into it. Here are the things that have been checked so far:

Replaced both cam and crank position sensors.

Checked that the cams are lined up properly.

Checked the wiring as recommend by Charlie_M above (Thanks!).

Checked the condition of the reluctor ring (can anyone provide a picture to compare?).

Checked the trigger wheels on the end of the cams.

Replaced the battery (it was dead, not that we thought it caused the code).

Inspected wiring harness for any defects.

The only idea left is to take out the catcams and replace them with OEM cams. That will set me back about 800 euros for parts and labor (not counting what I spent on the catcams). That may or may not fix anything, but it's about all that we haven't checked out yet.

The other option is to replace the motor which will set me back about 3,000 euros. This would be a safer bet, but then I am stuck with a modified engine that doesn't work and has little resale value.

Any other ideas that I could take a look at?


----------



## Charlie_M (Mar 23, 2011)

Mesix said:


> Any other ideas that I could take a look at?


Only thing I can think of is the ECU itself. Even if you could borrow an AMU narrowband, to see if it solves anything.

Is there anything on your block that could cause the crank position sensor to sit out, farther away from the impulse wheel? The electical signal from a hall sensor (ie, CPS) is pretty sensitive to the gap.

Have you checked the timing from cam-to-cam? I'm sure you have, but there's recently been some threads on here where even very experienced mechanics get it wrong (and then degenerate into insults etc). That could be a problem because of the way the ECU tries to use the Crank PS and Cam PS when starting:

When starting, the ECU tries to use the 4-window cam ps sensor to locate TDC, so the spark can be timed correctly. This (usually !) lets the motor fire right away and is the reason Bosch/VAG uses that method. If using only the Crank PS, then the ECU has to wait much longer to locate TDC while starting. Once started, the revs are quite high enough for the ECU to rely on the crank PS alone. That may be why you can push-start OK (RPMs are high enough to use the cam PS directly?). 

But why CEL at 3500 RPM? I have NFI ... sorry. But I am sure the hard starting and the CEL at 3500 RPM have the same root cause.

Do you have any friends that work in electronics? It would be pretty simple (for them) to look at and record the signals from the crank and cam PS during a start attempt and during a run. Maybe you or he could see from the signal how the ECU is being confused.


----------



## hitop (Jan 25, 2012)

ask your mechanic who rebuilded your engine-did hi/she:facepalm:removed metal wheel(for camshaft/engine speed sensor) on your crankshaft when they did that? reason of that-?that wheel should be replaced every time when you pull it out of the crank.with new bolts!!!!!


----------



## Mesix (Jun 8, 2009)

I have (almost) resigned to the option of returning the car to stock form by replacing the motor. If I do this, I will sell the car and get something which is more plug-and-play. Even if I can get this beast running, there may be some serious issues getting it to pass the German TUV inspection before I can get it registered.

Thanks for all the suggestions. I will try a few more things on Monday before I get the replacement motor ordered up.


----------



## Charlie_M (Mar 23, 2011)

Mesix said:


> I have (almost) resigned to the option of returning the car to stock form by replacing the motor. If I do this, I will sell the car and get something which is more plug-and-play.


I'm sorry to hear that ... your motor build seemed quite solid and properly done; it is a shame that ECU/sensor gremlins have caused you this much trouble.



> Even if I can get this beast running, there may be some serious issues getting it to pass the German TUV inspection before I can get it registered.
> 
> Thanks for all the suggestions. I will try a few more things on Monday before I get the replacement motor ordered up.


I don't know anything about TUV inspection, but if TUV can cause problems for even a properly running, but modified motor, then I can certainly see your point. 

Too bad the motor is not in the US; I would gladly take it off your hands.


----------



## Mesix (Jun 8, 2009)

Charlie_M said:


> I'm sorry to hear that ... your motor build seemed quite solid and properly done; it is a shame that ECU/sensor gremlins have caused you this much trouble.
> 
> 
> 
> ...


The TUV inspector came out and looked at the car at the shop while he was inspecting another customer car. He saw that the paperwork said AMU and the head had AEB stamped on it. He indicated this may be a problem. I am also concerned that without the secondary air pump, the German emissions test may fail, but I don't know about this last point until I try it.


----------



## Mesix (Jun 8, 2009)

I am going to try to replace the trigger wheel sensors on the cams and if that doesn't work, I will replace the catcams with OEM parts.


----------



## Charlie_M (Mar 23, 2011)

Mesix said:


> I am going to try to replace the trigger wheel sensors on the cams and if that doesn't work, I will replace the catcams with OEM parts.


Mesix, any updates on this?

I think *both* your problems are related to the crank position sensor: I guess it is well know by megasquirt users that a bad starter (soon to fail) will generate a lot of electrical noise that interferes with the CPS signal. So in your case you could not start with the starter due to interference, yet it push-started easily.

Also, some 60-2 trigger wheels are known to have problems at high RPMS:



> What starts as a small noise spike at low RPM becomes a very large noise spike right in the spot where the missing tooth is, causing the ECU to lose synch. You'll see this problem manifest as the RPM signal suddenly spiking downward at high RPM, and the car acting like it's hit a rev limiter.


Both these above problems are from this page: http://www.diyautotune.com/tech_articles/vrsensor/megasquirt_vr_index.htm Yeah, I know megasquirt is not Bosch, but, hey, it's a start. 

There are a few other current threads that mention loss of sync with the stamped trigger wheel (http://forums.vwvortex.com/showthread.php?5614837-welding-the-trigger-wheel-to-the-crank) and a 'dead band' in the dyno chart just like yours (http://forums.vwvortex.com/showthread.php?5611305-1.8-BT-loss-of-power-at-4400-rpm) Another possible cause for the dead band is listed in that last thread: spark problems at max boost -- check that thread for recommendations and see if it applies to your motor.


----------



## Mesix (Jun 8, 2009)

I am reviving my old thread with an update. After no love from the previous mechanic for several months, I have moved the car to another mechanic who has more experience with modified motors (but less experience speaking English which causes some issues...but that's another story all together). I did not replace the camshafts. The only things which have been replaced on the car are the crank and cam sensors (and the battery, but that was die to sitting too long and not part of the engine work).

The new mechanic says that he does not believe the problem to be mechanical, but rather electric. While the engine code seems to indicate that a sensor may be causing it, he says that the electric timing seems to be off and recommends replacing the computer. More specifically, he believes that the firing of cylinder 2 and 4 is not correct.

The current problem has existed with three different ECU programs. The car originally had a chip from APR installed. The APR EMCS module was removed and a stock VW/Audi ECU was installed. After the stock unit was installed, the ECU was flashed with a standard Eurodyne Stage 1 file. The same problems existed in all three ECU configurations. Would replacing the ECU with another stock ECU make any difference? Is there anything which I can do with the Eurodyne software which might help?

If I replace the computer, does it make sense to upgrade the computer? I have read that newer widband computers in later 20v motors are better. I am also curious if there are any aftermarket computers or newer VW/Audi computers which might be better. Can someone with more experience in ECU options point me int he right direction?


----------



## kapllan56ace (Feb 6, 2010)

have u solvd the problem


----------

