1985-1998 [Subscribe to Daily Digest] |
 | [Main 9000 Bulletin Board | BBFAQ |
Prev by Date | Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
"Shuddering" issue at times, need help Posted by dbreid [Email]  (#1192) [Profile/Gallery]
(more from dbreid) on Fri, 19 Feb 2010 15:59:35
Members do not see ads below this line. - Help Keep This Site Online - Signup
|
OK, I have asked about this for a while, and been working on this issue for probably a month, and I still don't have it fixed. The background is important, so I'll describe everything in as much detail as I can:
The Car________________________
1993 Saab 9000 Aero 5Speed with TCS
The Issue______________________
The car, at times, shudders. This is difficult to describe, but it feels almost like the engine is "lugging". It can happen at idle, or it can happen at any RPM range while under load or not. It isn't like it only happens when pulling up hills, or only at idle. It can happen when sitting at a light, and either come and go (meaning the engine runs fine for 30 seconds, then runs badly for 30 seconds, then runs fine for the rest of the duration of the light without me touching anything...) or be more persistent. It can happen while driving in 5th at 80mph down a hill.
It has nothing to do with temperature. For example, it can happen the first time I start the car in the morning immediately, or it can happen when the engine is nice and hot.
It has nothing to do with RPM (as far as I can tell), though sometimes when I "Rev" at a stoplight, it can "heal"itself. But it doesn't seem to be RPM or load related.
Background on what I have tried______________________
At first I thought it was a bad DI. It isn't. I bought a new one (Dealer), and it did nothing.
Then I thought plugs. I put in a new set of NGK's (with the R for resistors) capped to .95mm. No change.
Then I thought Fuel pump connections. Not that. Connectors are perfect, and I cleaned them and checked the connectors.
Then I thought Vaccuum leaks. I have checked all the vaccuum lines I can find, and replaced as many as I could find. No difference.
Next I thought it might be ETS, but I haven't had any faults while this problem is happening (I have an ISAT, and there are no ETS or Trionic codes)... :(
I then thought it could only really be related to Trionic. So I narrowed it to one of three things (or so I thought)
1.) The Crankshaft position sensor. My theory was that if that was failing or shorting, that it wouldn't give a good swuare wave, and cause Trionic to mess up.
2.) The Fuel Pump. Thought that if that was dying, I might have low fuel pressure, which might piss off Trionic.
3.) The O2 sensor. Theory was that if this was failing, the car might run way righ, and cause the poor running.
So I took it to a local Indy (SAF, site sponsor, really nice guys!) and they tested:
1.) New MAP sensor - made no difference.
2.) Fuel Pressure was good. Didn't seem to be fuel.
3.) Crankshaft Position Sensor was giving a great wave signal, so no issues there.
However, they noted that while driving, the output of the O2 would go "Flat" when the car acted up. They thought it might be as simple as a bad O2. So we put a new (OEM) one in, and at first that seemed to cure it. But I drove it over the next few days, and the issue is completely back, and the O2 didn't solve it.
So I am at a bit of a loss on where to look next. I get no Trionic Codes (but I have the Trionic manual and an ISAT, so I could do a fair bit of testing, if I knew which part to focus on).
Any advice on where to look next? I want to be methodical, and eliminate things, so I am open for zany suggestions. One thought I had was that it might be a bad ground some place that is intermittent?
Thanks in advance for any help.
-Dan
, Fri, 19 Feb 2010 15:59:35 <-- Viewing This Message, Thu, 25 Feb 2010 16:20:24, Tue, 23 Feb 2010 13:37:00, Mon, 22 Feb 2010 18:41:02, Tue, 23 Feb 2010 16:51:16, Tue, 23 Feb 2010 16:53:25, Tue, 23 Feb 2010 23:34:31, Sat, 20 Feb 2010 23:53:41
, Fri, 19 Feb 2010 21:51:56, Sat, 20 Feb 2010 23:51:26, Sun, 21 Feb 2010 01:34:55
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
