Power FC Shaky Idle, Won't rev past 1k but 2-3k fine
09-04-14, 06:12 PM
#1
Shaky Idle, Won't rev past 1k but 2-3k fine
Car:
FD
400lph pump & FPR set to 60psi
ID1000 Primaries / ID2000 Secondaries
New street ported block
Large Turbo
Stripped efi harness to bare minimum. Have main sensors plus the BAC.
Only vac lines are BOV, FPR, Gauge, and MAP.
E85
Gm 3bar
New car build and it's too far from stock to use a stock ecu to see if I'm having other issues.
The very first issue I had was the PFC wouldn't read CAS signal. I had to shim the sensors closer to the trigger wheel to even read.
I set the TPS to default values and have set the injector tables for ID's
The car has had a base map created by a known tuner but it's having a hell of a time idling and free revving the engine.
The idle is super lumpy and shakes the car. We were never able to get it to rev. Touching the throttle makes it start to hesitate and backfire like crazy. We never laid on the throttle due to this. Last week we tried just stabbing the throttle as soon as it started up. To our surprise, it revs like the car should and was fine around 2-3k rpm. If you let it go back to idle, it wants to die out or hesitate again and not rise in rpm.
Any thoughts?
My only things I can think of are primary injectors firing, Getting Spark, MAP sensor reading right values, TPS off, CAS sensors missing signal?
Next week I am going to take the UIM off and disable the fuel pump, then put light bulbs in the primary injector sockets to see if they're both firing. I'm pretty sure they are , but I put in new ID plugs so maybe a pin is loose.
Then I'll use a timing gun to verify spark in each wire.
Map sensor has the filter on it with new hose and is connected to back of UIM.
Might shim the cas sensors a little closer if this all fails.
FD
400lph pump & FPR set to 60psi
ID1000 Primaries / ID2000 Secondaries
New street ported block
Large Turbo
Stripped efi harness to bare minimum. Have main sensors plus the BAC.
Only vac lines are BOV, FPR, Gauge, and MAP.
E85
Gm 3bar
New car build and it's too far from stock to use a stock ecu to see if I'm having other issues.
The very first issue I had was the PFC wouldn't read CAS signal. I had to shim the sensors closer to the trigger wheel to even read.
I set the TPS to default values and have set the injector tables for ID's
The car has had a base map created by a known tuner but it's having a hell of a time idling and free revving the engine.
The idle is super lumpy and shakes the car. We were never able to get it to rev. Touching the throttle makes it start to hesitate and backfire like crazy. We never laid on the throttle due to this. Last week we tried just stabbing the throttle as soon as it started up. To our surprise, it revs like the car should and was fine around 2-3k rpm. If you let it go back to idle, it wants to die out or hesitate again and not rise in rpm.
Any thoughts?
My only things I can think of are primary injectors firing, Getting Spark, MAP sensor reading right values, TPS off, CAS sensors missing signal?
Next week I am going to take the UIM off and disable the fuel pump, then put light bulbs in the primary injector sockets to see if they're both firing. I'm pretty sure they are , but I put in new ID plugs so maybe a pin is loose.
Then I'll use a timing gun to verify spark in each wire.
Map sensor has the filter on it with new hose and is connected to back of UIM.
Might shim the cas sensors a little closer if this all fails.
09-08-14, 01:00 AM
#2
An update to anyone with similar issues.
TPS was at 1.5v at closed position. Replaced TP and it's now at 1v closed and 4.99 open.
We shimmed the CAS sensors so they are now 1/3-1/2 millimeter away from the trigger wheel and it's now getting a much higher resolution and is idling and revving much better.
Before the shimming, the tach would show 3500rpm and the PFC would show 2500-3000 rpm, so it was missing trigger signals.
With it shimmed, the tach and PFC are almost identical.
I'm a little worried about the seriously small clearance from the trigger wheel so we're going to get some replacement CAS sensors in case they are some how out of spec.
I don't think it's interference EMI because when I reworked the efi harness, I left the shielding around them and tested the ground for them(connected to floor board nut. It's also more of a not seeing signal versus stray signals.
TPS was at 1.5v at closed position. Replaced TP and it's now at 1v closed and 4.99 open.
We shimmed the CAS sensors so they are now 1/3-1/2 millimeter away from the trigger wheel and it's now getting a much higher resolution and is idling and revving much better.
Before the shimming, the tach would show 3500rpm and the PFC would show 2500-3000 rpm, so it was missing trigger signals.
With it shimmed, the tach and PFC are almost identical.
I'm a little worried about the seriously small clearance from the trigger wheel so we're going to get some replacement CAS sensors in case they are some how out of spec.
I don't think it's interference EMI because when I reworked the efi harness, I left the shielding around them and tested the ground for them(connected to floor board nut. It's also more of a not seeing signal versus stray signals.
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