Help weird idle
- Thread starter 89supraa
- Start date
Sorry, I know my last post is kinda random at this point in the thread, but I'm trying to fix a fast idle problem and I saw the mythbuster post about vacuum leaks causing high idle on different fuel injection systems. I've got an 87' 7mgte and I've been replacing vacuum lines thinking that was the cause of my 1200-1500 idle. PLEEEASE tell me that I can stop looking for vacuum leaks and start pursuing electrical issues instead. I'd love to find out that it's my TPS at this point.
---------- Post added at 09:38 AM ---------- Previous post was at 09:38 AM ----------
Thanks! I appreciate it. I'm at work, so I didn't have time to reference back.
---------- Post added at 09:38 AM ---------- Previous post was at 09:38 AM ----------
Thanks! I appreciate it. I'm at work, so I didn't have time to reference back.
The TCCS has it's roots (as do most EFI systems) in a Bosch design. After all Bosch invented EFI.
L Type systems (the L is for "luft", the German word for air) directly measure air flow into the engine to determine load. D Type systems ("druck", German for pressure) determine load indirectly by measuring manifold pressure. Put simply if a system uses an AFM or MAF it's L Type. If it uses a MAP sensor it's D Type.
Leaks increase idle speed only on D Type systems. With L Type idle quality (mixture) is effected. Therefore, as long as your engine is still stock, you can stop looking for leaks as the cause of high idle speed.
Although it can be other things the TPS is a good place to start....
L Type systems (the L is for "luft", the German word for air) directly measure air flow into the engine to determine load. D Type systems ("druck", German for pressure) determine load indirectly by measuring manifold pressure. Put simply if a system uses an AFM or MAF it's L Type. If it uses a MAP sensor it's D Type.
Leaks increase idle speed only on D Type systems. With L Type idle quality (mixture) is effected. Therefore, as long as your engine is still stock, you can stop looking for leaks as the cause of high idle speed.
Although it can be other things the TPS is a good place to start....
Yeah, probably my next stop. My Idle Speed Control Valve had a nasty vacuum leak at it's base, so mounting that properly helped my rough idle, and idle at cold temp. But after I drive the car and get it warm, she's back to 11-1300 rpm...
