Need Help: Loss of power & rattle noise ONLY at 2-3k rpms

[TDS]

1990 KAE ~30k-40k mi on rebuilt engine

I just recently noticed a loss of power until ~2.7k rpms. I can floor it and it just lags. Once it goes past 3k rpms, it pulls normal again. During that rpm range I also notice a rattle noise similar to the timing chain rattle noise on cold start ups. Engine feels a little unstable (shaking), exhaust makes more popping noises at idle (I already had an exhaust leak). I am really good about doing reg maintenance and tune ups. Could this mean I need to replace my timing chain

Thanks for all the help


Modified by TDS at 9:55 AM 12/26/2007

[TDS]

bump.


Modified by TDS at 5:07 PM 12/26/2007

[Uncle_staliN]

sounds like your timing is off a bit

[biotoxic07]

MAF. i had the same problem. took it apart and sprayed some throttle body cleaner threw it. slaped it back on and BAM no more sputter at low end. also you might want to pull codes. and reset the ecu. i did that today and after getting code 12,13, and 41..i reset it drove all day and it ran like a champ. pull codes again tonight and got code 55..all clear

[TDS]

I just cleaned MAF and throttle body a few weeks back. I don't have a check engine light on either.

I will check the timing this weekend.

After opening the valve cover and checking the timing chain, everything looks normal. Chain is not loose, neither does it show signs of wear. A friend who is a mechanic says it doesn't sound like its coming from the chain but from inside the motor.

I am removing emission to locate potential vac leaks. So far i found a crack on the of the hard lines coming off the manifold.

[biotoxic07]

yah im getting a sounds also but only when the car is under load. im thinking that im having a mean exhaust leak.

[TDS]

^Thats the only time i hear it too.

[biotoxic07]

bump for a common problem

[TDS]

I don't see how an exhaust leak would cause a rattle in the engine unless your exhaust manifold i loose from the where it bolts to the engine. I've had an exhaust leak ever since i put on my crappy pacesetter header but i didn't always hear that rattle.

Anyways, i took off all my emissions this past weekend and the car now idles real nice and the motor is no longer rough. After doing some research here on NICO, I only kept the brake booster line and ran a vac line from the hard line coming off the top rear of the intake manifold to the FPR. I also drove around for a while and i didn't feel the lag that was there before...

...BUT now I have a huge screeching sound from one of the belts/pulleys at start up for a few seconds. I am leaning towards the alternator pulley. The belts are 2 yrs old with 26k mi on them. I also seem to have installed the throttle cable incorrectly because my gas pedal has no pressure and I can floor it without any resistance. Anyone experience any of these two issues?
Modified by TDS at 11:31 PM 1/2/2008