jlturpin

I have an issue/hiccup around 5K rpm, it only happen then and seems to clear up by 5300 rpm. AFR's are spot on, boost stays steady, new plugs, new coil. Engine has less than 2K on it. Thanks for your help.
http://www.youtube.com/watch?v=t89zO2NJbnY

toddk911

Cap and rotor new?

Only times I have had the same problem were plugs, cap/rotor, choking point in the intake track or lean spot.

So that leaves you with cap/rotor or check your intake from filter to TB and check for leaks, holes, anyhting strange, etc.

jlturpin

I pulled the VR PB, problem followed
I replaced KLR, Problem Followed
I replaced the DME Relay, Problem followed
I replaced the DME, Problem followed
Changed Cap and Plug wires, Problem followed. Rotor is brand new.

No intake leaks.

toddk911

Your a/f datalogs reveal no lean/rich spikes around 5K rpm?

Does it happen in all gears and even off boost or only load based hiccup? i.e. in 3rd, 4th gears or at heavy/full boost?

jlturpin

It happens worse is 3rd, but still happens in 2nd. 1st is too short to tell. I do have data logs and no spikes. If I go through the problem are part throttle I am pretty sure it is clear. Will verify

spyder348

Check power and grounds my geuss is an electrical interference at back of motor by bell housing where ground and power cables run along close to speed/reference sensors. Poorly insulated wiring or small shorts in wires back there have caused issues at a certain rpm in all gears. Same feeling as having a dead spot on the original AFM, where the contacts on the resistor strip inside wear a small hole on the strip causing a hiccup when meter passes that spot can notice it more under load.

jlturpin

Pretty sure I found the issue today, will verify tomorrow. All test are pointing to the O2 sensor.