B6 Stutter

[skeeters_keeper]

Well i hope you found it! i know one of the first things i did was make sure my grounds were VERY clean and tight, i even added an extra jumper from the manifold to a ground during testing to check.

as i recall, someone else found that a ground was the cause of a similar problem... i figured that would have been one of the first things you checked!

Well, i hope thats your problem because that would be a very easy fix perhaps that is other folks problems as well.

i just sealed (or attempted to seal!) my exhaust leaks this AM, since it was leaking just past the headder i'm thinking perhaps that was causing my 02 sensor to see something funy? not sure but i'll find out soon i suppose!

[kzbill]

Still screwed up, even with a dedicated ground

[Festiva_tunner]

Check the alignment on your distributor sounds like its spun some . . . also take your injectors to a test facility to make sure they are all spraying correctly if the distributor adjustment doesnt work . . . there should be a bolt near the base of the distributor, the hole is slotted adjustment will retard/advance spark

[wrestler3025]

I had my fuel injectors ultrasonically cleaned at WitchHunter performance and they flow matched them as well, and it still has this problem. The distributor only goes in one way, so that isn't the problem, and timing is dead on.

[kzbill]

Waiting for my second Cardone VAF the first was bad out of the box.
The factory seal on the top was not even opened on the top it looked like they never opened it up, Re-manufactured? it looked as though they cleaned and painted it. Then stanped numbers and inspection marks on it and shipped it to Autozone.
I e-mailed Cadone's Ethics department, asked them if this may not be fraud. waiting for an answer! I also gave them a better Core than the Re-manufactured one they sent me.

[kzbill]

I am going to take it to a local manufacturer of ingnition and computer control parts. Wells Mfg. it is about 30 mi. from here and I know one of the service trainers. He is going to use it for a training unit to find the problem then return it fixed and I will be able to report to all on the fix. I will be taking it next week and will have to wait a few days while they track it down.
This is a national supplier of ingnition and control parts.

[skeeters_keeper]

well i can't wait to hear what they find out the problem is!!

but for now, i've got a lil update on my problem:

for my b-day on thursday my dad got me a handheld digital tach/multimeter, so i can finally tell how fast my engine is spinning! It was turning at about 850rpm at idle, so i adjusted it down to right on 720rpm. then i checked the TPS, and it was quite a bit off! so i set that, and then re-set the idle (it was idling a bit slow at that point, 550-600rpm) and then i set my timing, and the mark was actually in the right place! (the mark i made, not the mark on the crank pully i still have no idea whats up with that). i had to turn the disty a little to get the timing at about 11* BTDC. then i checked teh tps again, and it was still good, checked the idle speed and timing again and all was still good. re-set the ECU, fired it up and let it idle for about 5 min so the ecu could set itself, then took it for a spin. CONSIDerable increase in "pepiness", especially at lower rpm. i drove it for a few miles, and NO check engine light!!! i thought everything was fixed! after about a 6mi drive i was 1/2 mile from home.... and my engine light came on. code 17. GRRR.

i also filled up yesterday and got 27mpg. something is still wrong, but i have no idea what! the only drivability issues now are:

1. when its been runing, i shut it down and then fire it up it fires right up and the the rpms drop and it dies, most of the time. if i give it a lil gass right after i fired it up it will then idle down to its normal speed and stay there at a steady 720rpm.

2. it still misses ocasionally at idle, just sorta "pop's" a little. idle speed is pretty steady though, varying only by 10-20rpm.

3. that blast check engine light which i can't figure out.

i imagine all 3 are somehow connected, any more ideas are VERY welcome! I just reached my 500mile mark on the engine, so i will be changing the oil and re-torquing the head bolts on tuesday i hope.

[ajb999]

2. it still misses ocasionally at idle, just sorta "pop's" a little. idle speed is pretty steady though, varying only by 10-20rpm.

mine does this too but only when warmed up so i think it is probably the o2 sensor.

[funky technician]

your does sound like an O2 sensor, like its having trouble keeping up with the fuel demand

[skeeters_keeper]

its a brand new bosch universal fit. put it in with the new engine. I checked the reference voltages and i was getting .5-.7 volts at idle, which is normal though perhaps a little rich. right now i'm leaning towards too much fuel pressure, maybe a bad FPR? i'm going to try to hook up a fuel pressure tester tonight, it seems like i will have to install it in-line just after the fuel filter b/c there is no connection on the fuel rail.

Code 17 is an o2 sensor code, but its not teh o2 sensor fail code. there is a different code thats supposed to be set if the o2 sensor or wiring is bad, this one is just saying that there is a "fuel pressure problem or ignition problem or air intake leak", i'm quite sure theres no intake leak and ignition *seems* good... so next thing is the fuel pressure.

[kzbill]

could leaking injectors make it run too rich? mine is too rich.
How many people that are having this problem, have the optical distributor? (the one with the round metal shield under the cap)
The ECU that was in mine is a denso #B37618881-D, D being the only difference I can find in the fuel injected ones I find A, B, C, D. and a Ford part number.
What years are the problem cars?

[kzbill]

This is the report I got from my friend this am. he is checking the whole thing over. and trying to find the intermittant power loss issue.
B6 Stutter

"How about this? I scoped the ignition primary signal and the Hall Effect pick-up coil…..The pick-up had a spike in it that resonated into the ignition system. I cleaned the grounds and the spike is gone. With the clean signal I don’t hear the misfire/popping I was hearing before at higher rpm’s.


It appears the front pulley is mounted in the wrong position. I went through a manual mechanical timing set up this am and made my own TDC mark on the pulley. I then searched through the wires over by the master cylinder and found that the wire that shut the motor down when grounded is actually a pigtail for the coil primary circuit. I found the correct wire and checked timing; it was at 20° advanced. I dropped it down to 10° with the correct wire grounded.


Flashing codes I’ve got them for the VAF sensor and the CKP sensor. The CKP is explained by the spike in the pattern, the VAF I don’t understand. They don’t give an expected value at any PRM so I can only guess that doesn’t matter, only if the signal is missing or there (half full/half empty). The “good Festiva” scope trace has the VAF signal in it. At idle the voltage is about 3.10 volts, I’ve got no noise or signal break down throughout the pattern. Could the sensor have been unplugged with the engine running at some time?

I’ll take it for a test drive this afternoon but seeing it was intermittent I probably won’t feel it’s solved until you put some miles on it."

[skeeters_keeper]

It appears the front pulley is mounted in the wrong position. I went through a manual mechanical timing set up this am and made my own TDC mark on the pulley. I then searched through the wires over by the master cylinder and found that the wire that shut the motor down when grounded is actually a pigtail for the coil primary circuit. I found the correct wire and checked timing; it was at 20° advanced. I dropped it down to 10° with the correct wire grounded.

sounds like my pully problem! except i'm quite sure mine is mounted correctly :s i also made my own TDC mark and thats what i've been (successfully) setting my timing to.

Keep us updated, sounds like that guy is on the right track at least!!!



UPDATE on my car now:

I picked up a fuel pressure tester yesterday, i was running at almost 70psi at idle :shock: so i pulled off the return line and blew threw it, and could hear the air going into the tank. So i replaced the FPR with the one from my B3, which is almost identical just the line for the return line is a little longer. Now i'm running at 30psi!!! Can't catch a break, can I? i go from way to high to a little too low (its supposed to be 38-44psi at idle). Any way i re-set the ECU, and then took it for a little drive! no CEL, and it doesn't smell like its running as rich as before. Also it doesn't miss at idle any more (yet). AND it picks up a little better, seems like every time i re-set the ECU it has more power untill the CEL comes on again.


SO, i'm not sure why its only at 30 PSI but thats better than 70. If anyone has a known good B6 FPR they'd like to send my way for testing purposes that'd be well but theres no way i'm paying $80 for a new FPR!!


now i'm off to try to replace a watter pump pulley bolt... i must have over-tightened it because i just happend to notice that the head of the bolt was missing today (it looks twisted off but i'm sure it was there before!).

and i have a lot of school work to do :/

[kzbill]

I thought the pulley was mounted on correctly too. I have to check it now that I have the car back.
it runns better than ever.
The offending ground was called a "sensor ground" it is located on a metal bracket mounted on or near the thermostat housing on the engine. It is a ring terminal with two black wires in it. The sensor ground is part of the engine harness when I swapped engines I obviously missed cleaning that ground. The engine I put in had 90,000 or less mi. on it but had sat, inside, for about ten years.
plenty of time to corrode the connection. The connection cased spikes to appear on the sensor outputs to the ECU. The spikes caused symptoms from a very slight miss on Idle, to rich fuel mixture, and the intermittent stalling. It immitated an O2 sensor failure caused a VAF code and other annoying things. So even the the code outputs were strange.
My friend the "diagnostition" used a scope to see the spikes. He said it is very common to have Asian, and european cars, even the top of the line european cars to have bad grounds. He said grounds are the most common problems on BMWs and Volvos.
So just think of yourself as driving an orphan Beemer.
And thanks guys, many people may find thier problem this way
Bill

[kzbill]

it did it again this am.