Ignitor Partial failure possible

racerx9146 · #1 12-01-2007, 10:36 PM

My initial question is: Is it possible to have weak ignition module (ignitor)?

Now the background

Been fighting a issue with my 92 SVX powered Vanagon. I have read just about every troubleshooting case on this forum and tried many fixes with no avail so I thought i would throw myself on the mercy of the group and see if anyone can think of anything I have missed.

1992 SVX (approx 150K miles)

Symptoms

Problem has developed gradually over last 6 months
Upper RPM power seems poor but will rev out
Slow starting sometimes(4 or 5 cranks)
Stumbling at 1st start but problem seems to lessen when outside temperature is low (below 60 degrees F)
Performance is sluggish, like a 25% loss
occasional cutout under very high load (happened twice, only for a second)
Idles perfectly at 600 RPM but seem a little rougher like it should almost like a soft misfire.
Sometimes smells richs at start
Seems to run hotter than it used too
Engine does not rev as freely as it used too (in neutral)

Current troubleshooting performed

No current or stored codes present
Replaced both injector rails with used set, no change
Replaced 1 bank of coils with used set, moved 1st set to other side, no change
Tested coils with coil over plug tester, all report good
Replaced TPS, no change
Tested auxilary air valve, open when cold, closed when warm
Tested for intake leaks
Checked all Vacuum lines, replaced those under manifold less than 1 year ago
Leakdown test - all cylinders report 20%
Replaced ECU coolant temp sensor
Both O2 sensors are new and Select Monitor shows them cycling (high to low)
Tested fuel pressure regulator
Replaced air filter, fuel filter, fuel pump
Tested fuel pressure twice
Replaced NGK irridium plugs with new
Cats are flowing freely (not blocked)
Throttle body was cleaned 1 year ago
PCV is fairly new

Whats left?

Partially failed Ignitor, might explain why problems seem less apparant at cold ambient temps? Is this possible?
Cam angle sensor? Wouldnt this throw a code?
Slipped timing belt? Would it even run this good?
Iris system not working?
Crank sensors? Tach works fine!
EGR system, could it cause these problems?

Thanks for any help you can provide. I have the Stage 1 chip and the crush mod has been performed (did help with stumble) I love this engine when all is well!

John Daron

Trevor · #2 12-02-2007, 12:21 PM

Quote:

Originally Posted by racerx9146

My initial question is: Is it possible to have weak ignition module (ignitor)?

Now the background

Been fighting a issue with my 92 SVX powered Vanagon. I have read just about every troubleshooting case on this forum and tried many fixes with no avail so I thought i would throw myself on the mercy of the group and see if anyone can think of anything I have missed.

1992 SVX (approx 150K miles)

Symptoms

Problem has developed gradually over last 6 months
Upper RPM power seems poor but will rev out
Slow starting sometimes(4 or 5 cranks)
Stumbling at 1st start but problem seems to lessen when outside temperature is low (below 60 degrees F)
Performance is sluggish, like a 25% loss
occasional cutout under very high load (happened twice, only for a second)
Idles perfectly at 600 RPM but seem a little rougher like it should almost like a soft misfire.
Sometimes smells richs at start
Seems to run hotter than it used too
Engine does not rev as freely as it used too (in neutral)

Current troubleshooting performed

No current or stored codes present
Replaced both injector rails with used set, no change
Replaced 1 bank of coils with used set, moved 1st set to other side, no change
Tested coils with coil over plug tester, all report good
Replaced TPS, no change
Tested auxilary air valve, open when cold, closed when warm
Tested for intake leaks
Checked all Vacuum lines, replaced those under manifold less than 1 year ago
Leakdown test - all cylinders report 20%
Replaced ECU coolant temp sensor
Both O2 sensors are new and Select Monitor shows them cycling (high to low)
Tested fuel pressure regulator
Replaced air filter, fuel filter, fuel pump
Tested fuel pressure twice
Replaced NGK irridium plugs with new
Cats are flowing freely (not blocked)
Throttle body was cleaned 1 year ago
PCV is fairly new

Whats left?

Partially failed Ignitor, might explain why problems seem less apparant at cold ambient temps? Is this possible?
Cam angle sensor? Wouldnt this throw a code?
Slipped timing belt? Would it even run this good?
Iris system not working?
Crank sensors? Tach works fine!
EGR system, could it cause these problems?

Thanks for any help you can provide. I have the Stage 1 chip and the crush mod has been performed (did help with stumble) I love this engine when all is well!

John Daron

Greetings John,

Thank you for going to much trouble in setting out an exact statement regarding your SVX, including symptoms and areas covered to date. It is seldom that this sort of effort is recorded. It is apparent that you have approached the problem in a very logical way.

The igniter in effect comprises six solid state relays. The failure of a solid state switch is not usually intermittent and engine load should have no affect. It has not been reported here that the igniter is in any way a commonly faulty. However nothing can be taken for granted in this regard and one must depend on a logical approach.

(5) When the TPS was replaced, did you set it properly by measuring the voltage output at closed throttle? Refer the how too section, or my locker for details.

(6) Excellent that you have checked the AACV as few have done so.

You rightly have doubts in some areas due to no fault codes being recorded, However I am sure that you appreciate that the system is not infallible. As a result all sensors must remain suspect.

The outstanding item in your list is the air flow sensor (MAF). You report a possible rich mixture and improved running at low temperatures. Faulty sensing of the intake air flow could very well result in all the symptoms you describe.

I respect and admire you for providing your complete identity.

Sincerely, Trevor Sheffield.

racerx9146 · #3 12-03-2007, 11:40 AM

Thanks for the help Trevor. I have a friend who lives about a hour away with a parts car. Seems like the next (cost effective) step is to visit him and try to swap some parts starting with the MAF sensor. I imagine thats not a cheap unit!

It also appears like the cam angle sensor has caused people "difficult to solve issues". That might be my next part to try after the MAF.

thanks John Daron

racerx9146 · #4 02-15-2008, 02:20 PM

Old post but I wanted to let everyone know that replacing the MAF sensor fixed all my wierd problems. Thanks for the help.

John Daron

Trevor · #5 02-15-2008, 02:51 PM

Quote:

Originally Posted by racerx9146

Old post but I wanted to let everyone know that replacing the MAF sensor fixed all my wierd problems. Thanks for the help.

John Daron

Great news Daron,

It is very worthwhile when members report outcomes, as this adds valuable information the knowledge base.

We struck the jackpot.

However after all your work eliminating the many possibles it was not hard to pick the Joker.

Cheers, Trevor.

TomsSVX · #6 02-15-2008, 03:06 PM

I saw you had asked a question about the timing belt. Maybe it will help others who read this or maybe it will help you in the future. Yes, if the timing belt jumps a tooth or two on the passenger side pulley, it will run very strangely and no error codes will be reported. Glad to hear it was simply a faulty MAF sensor. Good luck

Tom

lhopp77 · #7 02-15-2008, 03:21 PM

Did I understand this correctly--it was an SVX engine in a Vanagon?

Lee

TomsSVX · #8 02-15-2008, 04:03 PM

Yes Lee, it is a fairly common conversion these days. Smallcar has a ton of stuff for a conversion like this. Thats where I get my header flanges for the engine.

Tom

lhopp77 · #9 02-16-2008, 07:43 AM

Quote:

Originally Posted by TomsSVX

Yes Lee, it is a fairly common conversion these days. Smallcar has a ton of stuff for a conversion like this. Thats where I get my header flanges for the engine.

Tom

I know because several very fixable SVXi have been parted because of the conversion. The vans will make more money than a repaired SVX, but that still doesn't justify the cannibalism for an SVX lover. It actually makes me sort of sick.

Lee

TomsSVX · #10 02-16-2008, 07:51 AM

Quote:

Originally Posted by lhopp77

I know because several very fixable SVXi have been parted because of the conversion. The vans will make more money than a repaired SVX, but that still doesn't justify the cannibalism for an SVX lover. It actually makes me sort of sick.

Lee

I understand your anger and frustration. But you cannot convince everyone, I learned that quickly

Tom