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.