Throttle control issues... And more!
This issue had plagued me for months. This afternoon the car finally got so bad it's unsafe to operate on a public road. Where to begin...
Background: 2008 Elise SC (factory supercharged) Larini SC exhaust. Stock power train otherwise. Michigan car, now in California.
A few months ago on cold mornings the car started getting hard to start. Anything below about 50° and it would have idle issues. I'd never had that issue before. Soon the issue started resulting in failures to start and a P0638 code. After a ton of restarts eventually the car would idle and run. Before that it would surge between 1700 and 2000 rpm and have no throttle control. On any morning over 50° the problem would not occur at all. That's where we've been until this weekend.
It's been getting progressively worse and less temperature dependant over the last few days, along with a few new tricks! Upon first start today it did the usual cold weather thing, even though it was in the mid 60's. I finally got it running but it was loping like a cammed V8 and trying to stall. After about 5 minutes of driving it got better and drove fine.
Fast forward to after dinner, driving home. Started fine, only with a rough idle. Different idle though. Idle was normal but kept bogging, it would drop to about 600 every few seconds. Started driving home and on steady throttle input it would bog and the nose would dive, complete loss of power, but the exhaust is very loud in those moments like it's under tremendous load. It never got better. I finally made it to the freeway where the increased speed usually hides or cures the issue. At 65, steady throttle, it would bog, nose dive, and drop 5 to 10 mph while being very loud. Every time it would do this the temperature on the screen would drop to 158 then immediately climb back up to actual operating temperature. For the entire 20 mile freeway trip it did this every 5 seconds or so on average, but not rhythmically in any way. For one 2 or 3 second period I had no throttle at all and started moving over thinking it had died.
What I've fixed:
-Cleaned then replaced MAF
-Reseated all connectors on throttle body and ECU.
-Replaced entire intake assembly (mine was broken, thought maybe it was a leak of some sort.)
-Countless fault code checks and clears
-New catalytic converter (had a hard time getting it to pass smog when I brought it to California)
-Cleaned throttle body
-Checked all engine bay fuses
I think that's everything. I've run out of ideas and it's worse than ever.
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Perpetually broken2008 Elise SC
2000 Jeep Cherokee