Hey fellas I have a 89 trans am...I changed the plugs about a month and a half ago...plugs, wires, cap and rotor. This past weekend I changed the ignition coil which was corroded and seemed original. Anyhow I thought that was the fix for my car bogging down and losing power at low speeds, also thought it would fix hard start up. What else would cause these issues? Guess I should mention I have the 5.7 tpi engine thanks.

 

Have you checked fuel pressure? Any codes being thrown? (possible O2 sensor issue). Could also be a timing issue :x

 

no codes are being thrown..and i havent checked fuel pressure..that seems to be a strong candidate for the issue im assuming because i have to pump the pedal and rev my car to keep it started..with fuel injection i know you shouldnt have to do that..am i right?

 

correct you shouldn't ever have to pump the pedal with FI. I'd suspect low fuel pressure/bad regulator/clogged filter. As the regulator is controlled by vacuum. The lower the revs, the more vacuum, the more fuel is regulated. The higher the revs, less vacuum, the less fuel is regulated.

 

so how do i check that or is it the likely culprit? the fuel filter has been changed within the last 2-3 weeks..my car searches for a stable idle at times also

 

Are you sure there isnt any codes thrown? and that your bulb might just be burned out? Check/replace the bulb, or bring it to autozone or somewhere to have it scanned. It should be throwing a code. You can also borrow autozones fuel pressure gauge, you are looking for ~43.5 psi with the vacuum line unplugged from the regulator.

 

is the regulator right underneath the plenum in back of engine or is that the egr and the regulator sits further inside? also my engine light works...it comes on every now and again then my car seems to idle smooth when it does come on..but its rare that it comes on.

 

Intermittent SES lights generally point to a bad O2 sensor as the ECM doesn't attempt to collect any information from them until they are warmed up. Does the car run better when you first start it as opposed to when it's been running for awhile? Find your fuel rail, your regulator will be on it with a vacuum line going into it: http://www.eecis.udel.edu/~davis/z28...5/tpi-afpr.jpg

 

No runs kinda shitty most times....runs good on the freeway to about 3000rpms then stuggles seems like not enough gas or something....backfires out the exhaust while idling or when engine slow down by braking...

 

Im having a similar problem. Is it fine at high rpms and and idle shakey? Also does it have any pickup? And does it feel like its driving thumpy?

 

You have low fuel pressure. Get a Fuel pressure gauge from autozone, and check it.

 

[quote=BahN;4656776]You have low fuel pressure. Get a Fuel pressure gauge from autozone, and check it.[/quo

low fuel pressure is that caused by the regulator, injectors, or fuel pump? or which is a likely cause?