 Engine only starts on compression when hot |
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| velum |
 Jun 10 2011, 04:56 AM
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#1
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Member  Group: Members Posts: 50 Joined: 4-June 08 From: Montréal, Qc, Canada Member No.: 9,135 Region Association: None  |
My car is a '73 914-4 2L FI, and here is a description of the problem:
When the engine becomes hot, the car has less and less power at low RPM. On street corners, I have to rev the engine above 2000 RPM to get going without stalling it. When the engine is cold, this is not a problem. Also, if I have been driving for quite a while and the engine stalls, it will only re-start on compression. Cranking it won't start it. Last year, I fixed many things in the car, and I thought this problem would be resolved, but it hasn't been. Here is a list of parts that have been fixed: - My 037 MPS was leaking, so I replaced it by a none leaking 049 MPS (0 280 100 049 MPS) that I re-calibrated. In order to do this, I brought the car on the dyno. While the car was on the dyno, we noticed that the engine "preferred" to run rich, and that it did not have that much torque at low RPM. For someone not accustomed to it, the car easily gives the feeling it is gonna stall when starting in 1st gear. It has always been so, but it seems even more so since I changed the MPS. - I replaced the CHT. My 0 280 130 017 CHT was bad, so I replaced it with a 0 280 130 012 CHT, since the 0 280 130 017 is no longer available. I kept the ballast resistor in place. - The injector seals have been replaced. - The FI wiring harness has been replaced for a brand new one. Any idea of what to check next? |
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Replies(1 - 4)
| benalishhero |
Jun 10 2011, 05:42 AM
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#2
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Member Group: Members Posts: 313 Joined: 28-November 07 From: Portland, Maine Member No.: 8,384 Region Association: North East States |
Just a thought, try unplugging the air temp sensor that sits below the TPS when you reach operating temperature.
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| velum |
Jun 10 2011, 05:47 AM
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#3
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Member Group: Members Posts: 50 Joined: 4-June 08 From: Montréal, Qc, Canada Member No.: 9,135 Region Association: None |
QUOTE(benalishhero @ Jun 10 2011, 07:42 AM)  Just a thought, try unplugging the air temp sensor that sits below the TPS when you reach operating temperature. Hi Thomas, Do you mean doing this while the engine is on or off? And what should I observe? Cheers! JF |
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| benalishhero |
Jun 10 2011, 09:26 AM
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#4
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Member Group: Members Posts: 313 Joined: 28-November 07 From: Portland, Maine Member No.: 8,384 Region Association: North East States |
As soon as the symptoms arrive while the engine is running. Unplugging it will bring your idle back up. Again this is just a thought. My car does the same thing when it warms up if the sensor is plugged in. I just leave it unplugged and the car drives/idles fine.
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| Rockaria |
Jun 10 2011, 11:10 AM
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#5
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ZippidyDoDah... Group: Members Posts: 817 Joined: 2-May 03 From: Southwest, USA Member No.: 645 Region Association: None |
QUOTE(velum @ Jun 10 2011, 04:56 AM) ...engine stalls, it will only re-start on compression. Cranking it won't start it....- . I appologise for my ignorance up front. But what do you mean by "it will only re-start on compression"? EDIT: Ohhh... Push Starting, Roll down a hill, pop the clutch, Got it... |
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