my car, '88 S4 13BT 5 speed, seems to be having trouble in the higher revs when its under a bit of load like goin up a hill or when it has people in it, always the hight rev after bout 5800 to redline not consistant almost always there tho. It just kind of misses it goes brrrrrrrrrrr ~brarrp~ brrrrrrrrr~braarp~braaarp~brrrrrrrrrrrrrrrrrrrrrrr rm if that makes any sence?? i think its blowin flames out the exhaust when it misses like this. It has a K&N pod filter and a 2.75" custom exhaust. any ideas why it does this??

 

My first guess would be leading ignition. Check wires for leakage/resistance. If they are over 50,000 miles old, I would replace them for sure. Get a new set of plugs. Under load, they may be heating up and breaking down. Next guess, fuel. Replace the filter, check pressure. It should be 28 psi at idle, but more importantly 38 psi with the vacuum hose pulled. If the pressure is low, check that the fuel pump is receiving full voltage. My last guess is the line leading to the boost sensor on the passenger side shock tower (front). Make sure the line to it from the ACV has no leaks, and the line contains a pill (restrictor) in it to prevent boost surge. Hope some of this helps.

Irv, Keith's dad

 

thanks. Ill check the leads and plugs tonight, ive recenltly (within last 3 weeks) replaced the fuel filter, as the old one ripped inside and put all the crap in my injectors, which stopped the car pretty quickly. Ive since fixed that, but perhaps this problem could be to do with that? like a secondary injector not firing?? would this make a problem like that?