When it idles for too long the rpm bounce from 200 rpm to 1000 rpm and then dies. If i hit the gas sometimes it goes away and other times still does it. what could this be. I just replaced the ect sensor it was bad. When it starts cold it idles at 1500 rpm and when it warms up it sits at 900 rpm.

 

Check the fuel pressure. This can be caused by a faulty FPR.

 

brand new fpr, new fuel rail, new fuel pump, and new fuel filter

 

bump the pressure its mayb too low
happen to my car just bumped it a few pounds try it

 

IAC valve problem maybe?

 

fuel pressure sitting at 45.

will have to look at that IAC issue thank you..

 

i bought some used plug wires, mine did the same thing.. and when the engine was under load it would hiccup real bad between 2k-3500 rpm..

also, check your plugs to see if they are still good

good luck

 

plugs are new. and when it hiccups you can smell a lot of fuel. sound like the ecu is making up the difference.

 

45psi at idle is too high. Check the pressure with the FPR vacuum hose disconnected to verify that the FPR is faulty.

 

Also check the MAP sensor voltage to see if there is a vacuum leak before you replace the FPR.

 

if the motor hiccups and u smell fuel that means you aren't burning all your fuel..

which is probably ignition related if you are not throwing a code (o2 sensor)

i'd try new wires, or ur plugs could've mysteriously messed up. i'd check them again even though they are new

 

for my application its suppose to be between 40psi and 50psi. The AEM FPR is brand new. Big block I havent had a chance yet to look at the IAC valve But i will take it to my mechanic and have him look at it tommorow night. Getting new plugs before saturday for the tune up on the dyno. I will let you no if it was just a ECU issue that needed to be tuned or if it was a different issue. Thank you for all your input.

 

mechanic said everything looked okay. Said it sounds like the p72 ecu with a base map is not doing its job. He said the tuning on the dyno should take care of it... Will find out for sure come saturday...

 

I think its your spark plugs, check the gap...

 

will check it out saturday. thanks...

 

it was a complete map issue. they fixed it with the new map.
Now i have a new problem!!!!

On the dyno the car in 4th gear at about 2500 rpms woiuld start to bog down like it wasn't getting enough fuel. it was like the ecu was cutting off the fuel. it didn't matter if you let go of the pedal and floored it in 4th it still did the same thing.... in 2nd gear he was able to get to 7800 rpm. very stressful..... any ideas would be helpful. i am going to start to take off the msd sci plus igniton and go backwards from there to see if that solves the problem.... before i forget they replaced the map and tps sensor and that didn't fix it....