Missing/cutting out on high boost 91 200 20vt

itsav8 · 03-02-2009, 02:55 PM

Well I've been haveing an intermitant problem with my 200 20vt for a few months now..... getting the RPM sensor code.
Whats happening is the car is missing/cutting out on heavy boost.... sometimes... not all the time mind you. Me & Austin have swapped out the sensor (RPM sensor) four times now with used within spec ones we have laying around.
We have tried variouse things...but to no avail. So since I do not wanna toss $$$ @ the car for no reason I wanted to know what others think.
& yes I have the rite dizzy rotor! Plugs are 7A NGK's. We/Austin did pull one of the plugs & the electrode looked out of round... more like a triangle now. I was planning on maybe trying the Bosch plugs..... but I don't wanna toss that kinda $$$ for plugs if thats nmot the problem. I had a few bad plug wires... but we replaced them with known good ones back when I took the car to the dyno that made 220whp & 311ft lbs of torque with no missing... as I mentioned it's intermitant.
The cars all so got a new 710N valve, the old 3B WGFV works/clicks durring the output tests. I even put a //scar one in with no change. All the hoses are tight... we did a pressure test. WG diaphragm is good, I have a metal geared dizzy. The TPS works as it should, we/Austin took the TB off & cleaned it & adjusted the switch @ the same time.

The only code were getting is for the RPM sensor. Should I just belley up & buy a new one, or?????

V8QinNJ · 03-02-2009, 05:05 PM

Talk to BING on JFR, he was having the same issue on his S4 under high boost. I'm pretty sure it was the coil or plugs couldn't keep up at that pressure.

quattro_rocks · 03-02-2009, 07:24 PM

Just recently on my S6 the car would miss on high boost as well, but only once the car was warmed up.

On my audi 5000 quattro the wires and the distr. were not good. Your problem is ignition related as well i'm sure.

itsav8 · 03-03-2009, 02:08 PM

... sometimes the car will only get up 15lbs before it starts to stumble/miss. Some times the car will get up to 20lbs, ect... it has no set lbs# when it does it.
But all so as I've noted... I can drive the car like I f'in stole it with no missing or stumblin!

jurq · 03-04-2009, 06:28 AM

This would happen to my car when the PT was dying. I swapped in a stock ecu, and the problem was exacerbated, and I got the correct overboost/pt code from the ecu.

HTH,
Jim

itsav8 · 03-04-2009, 09:54 AM

& since you mentioned fuel pump I have just heard the gloriouse song from it today a matter of fact... funny you put the voodoo on my pump Jim?..LOL
I was going to upgrade the pump next Summer when I put this car away & build it up a bit more.
But I don't think it's fuel related.... I think it's ignition.... plugs maybe... I did mention how the round electrode is like a triangle'ish shape now.
I suppose I could try the Bosch plugs.

I suppose I could swap out the new bell housing sensors I got for my Blk 5sp & put them in DER20vt to rule that as being the problem. Just hard to believe thjat me/Austin have tried 4 RPM sensors now... all rite within spec & yet I'm still getting the RPM code... but then other times I'm not????

itsav8 · 03-04-2009, 09:55 AM

... Me & Austin are going to put the ECU in my car in his & see what happens. That should rule out a few things as well.

audiman4 · 03-04-2009, 12:19 PM

Not sure what all the logic is behind from what I've been told you should only use the OE plug. They're good enough for RS2 levels so should be good enough for your HP level as well. Especially since you seem to be noting some irregularity w/ the shape of the plugs in there now. Check SJM's site and also read the section below where he talks about plugs.

http://www.sjmautotechnik.com/troubl...ost.html#plugs

itsav8 · 03-04-2009, 01:28 PM

change the plugs.... I'll be preparing myself for the price tomorrow when I go to my guy & see what he's going to charge me for them... & I hate Bosch plugs!!!!!! Hell the 7A NGK plugs I'm using I think cost me near $6.00 each.

I'm all so going to OHM out my wires & there ends.
Copied & pasted some of Scott's instructionsVVVVVVVVVV
------------------------------------------------
For the 3B engine, the Audi OE ignition wires have a stranded copper wire and use resistive spark plug connectors that each have ~5k ohms. The other end of the ignition wire that plugs into the distributor cap has a resistive connector end with approximately 1k ohms.

In many cases the spark plug ends can have too much resistance and will cause a misfire under load, in some cases the resistance measurement will test OK, but you will still get a misfire due to the ignition wire/connectors.
------------------------------------------------

Thanx for the suggestion.

03-02-2009, 05:05 PM	#2
V8QinNJ AudiWorld Senior Member Garage is empty, add now Join Date: Sep 2006 Posts: 1,139	Re: Missing/cutting out on high boost 91 200 20vt Talk to BING on JFR, he was having the same issue on his S4 under high boost. I'm pretty sure it was the coil or plugs couldn't keep up at that pressure. __________________ _________________ Scott '90 V8 Quattro Papryus Metallic (SOLD) '90 V8 Quattro Pearl Metallic '90 V8 Quattro Crystal Silver Metallic '90 V8 Quattro Pearl Metallic (Parts)

03-02-2009, 07:24 PM	#3
quattro_rocks New Member Garage is empty, add now Join Date: Sep 2002 Posts: 236	I was also going to suggest coils but the 200 20v does not have coils. Just recently on my S6 the car would miss on high boost as well, but only once the car was warmed up. On my audi 5000 quattro the wires and the distr. were not good. Your problem is ignition related as well i'm sure.

03-03-2009, 02:08 PM	#4
itsav8 AudiWorld Super User Garage is empty, add now Join Date: Jan 2004 Posts: 3,097	I should all so mention.... ... sometimes the car will only get up 15lbs before it starts to stumble/miss. Some times the car will get up to 20lbs, ect... it has no set lbs# when it does it. But all so as I've noted... I can drive the car like I f'in stole it with no missing or stumblin! __________________ thanx Ron 2.6l 20vt stroker motor W/O a roof 91 V8 5sp mit 4.2 aka Black Betty 91 200 20v 22psi 90 v8q 3.6 not stock...gone but not forgoten :-(

03-04-2009, 06:28 AM	#5
jurq AudiWorld Senior Member Garage is empty, add now Join Date: Jan 2004 Posts: 1,972	Have you checked the fuel pump? Also, what PT do you have in the ecu? This would happen to my car when the PT was dying. I swapped in a stock ecu, and the problem was exacerbated, and I got the correct overboost/pt code from the ecu. HTH, Jim __________________ 1984 Scirocco MkII 1991 200 20v quattro Avant

03-04-2009, 09:54 AM	#6
itsav8 AudiWorld Super User Garage is empty, add now Join Date: Jan 2004 Posts: 3,097	I got the 2.5PT that ben supplies. Austin soldered it in. & since you mentioned fuel pump I have just heard the gloriouse song from it today a matter of fact... funny you put the voodoo on my pump Jim?..LOL I was going to upgrade the pump next Summer when I put this car away & build it up a bit more. But I don't think it's fuel related.... I think it's ignition.... plugs maybe... I did mention how the round electrode is like a triangle'ish shape now. I suppose I could try the Bosch plugs. I suppose I could swap out the new bell housing sensors I got for my Blk 5sp & put them in DER20vt to rule that as being the problem. Just hard to believe thjat me/Austin have tried 4 RPM sensors now... all rite within spec & yet I'm still getting the RPM code... but then other times I'm not???? __________________ thanx Ron 2.6l 20vt stroker motor W/O a roof 91 V8 5sp mit 4.2 aka Black Betty 91 200 20v 22psi 90 v8q 3.6 not stock...gone but not forgoten :-(

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03-04-2009, 09:55 AM	#7
itsav8 AudiWorld Super User Garage is empty, add now Join Date: Jan 2004 Posts: 3,097	..ALLSO....... ... Me & Austin are going to put the ECU in my car in his & see what happens. That should rule out a few things as well. __________________ thanx Ron 2.6l 20vt stroker motor W/O a roof 91 V8 5sp mit 4.2 aka Black Betty 91 200 20v 22psi 90 v8q 3.6 not stock...gone but not forgoten :-(

03-04-2009, 12:19 PM	#8
audiman4 AudiWorld Member Garage is empty, add now Join Date: Feb 2002 Posts: 379	You should change the plugs Not sure what all the logic is behind from what I've been told you should only use the OE plug. They're good enough for RS2 levels so should be good enough for your HP level as well. Especially since you seem to be noting some irregularity w/ the shape of the plugs in there now. Check SJM's site and also read the section below where he talks about plugs. http://www.sjmautotechnik.com/troubl...ost.html#plugs

03-04-2009, 01:28 PM	#9
itsav8 AudiWorld Super User Garage is empty, add now Join Date: Jan 2004 Posts: 3,097	Yeah me & Austin discussed the out of round electrode & I figured I'd have to change the plugs.... I'll be preparing myself for the price tomorrow when I go to my guy & see what he's going to charge me for them... & I hate Bosch plugs!!!!!! Hell the 7A NGK plugs I'm using I think cost me near $6.00 each. I'm all so going to OHM out my wires & there ends. Copied & pasted some of Scott's instructionsVVVVVVVVVV ------------------------------------------------ For the 3B engine, the Audi OE ignition wires have a stranded copper wire and use resistive spark plug connectors that each have ~5k ohms. The other end of the ignition wire that plugs into the distributor cap has a resistive connector end with approximately 1k ohms. In many cases the spark plug ends can have too much resistance and will cause a misfire under load, in some cases the resistance measurement will test OK, but you will still get a misfire due to the ignition wire/connectors. ------------------------------------------------ Thanx for the suggestion. __________________ thanx Ron 2.6l 20vt stroker motor W/O a roof 91 V8 5sp mit 4.2 aka Black Betty 91 200 20v 22psi 90 v8q 3.6 not stock...gone but not forgoten :-(

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