missing, and hesitation

[mizono]

setup

I have a redtop sr20det with intake, turbo/02 housing, down pipe, exhaust, and t28 turbo.

problemIt seems like I can't hold a steady rpm, for example if I rev the motor to 2k rpm and try and keep it there it misses and dips a little bit. I've also noticed that when this happens my a/f goes lean and then back to 14.7. This also happens while cruising at a steady speed I can slightly feel the motor dip in power as the a/f goes lean and then back to 14.7

what I've done to try and resolve the issue

I redid my timing as shown on the frsport web page http://www.frsport.com/How-To-....html changed coil packsfixed all boost leaks

[burntricer]

check your timing via CAS, and verify your mechanical timing, any engine codes? can you adjust your idle with your iacv?

[dtowndrifter]

i had this problem last week...thought it was my leaky bov/ boost leaks, vac leaks...then thought it could be a ground..this was all after the tps and timing was in spec..then checked cts..coil packs..tps...cas..maf..knock sensor...fuel regulator....f.pump is good...new o2...all sensors were swapped out..i mean all..in other words all sensors were good...

had this problem once before the ecu.. and it was my tps/throttle sensor..needed adjustment..

turns out my ecu took a crap on me...it works.. but it stumbles and hesitates with the ecu..

[mibave]

i had this happen to me also first time it was a wire for my maf and well the last time it happend it was a ground alternator

[mizono]

redid maf wiring, redid knock sensor wiring, wired up consult port, and adjusted timing. I was beginning to think it was the cts until I looked at the sensor values using the consult port and the cts looked good. finally I put in a resistor for the knock sensor (470k ohm) and the problem went away.

The symptoms were sometimes the idle would stumble and die after boosting. After warmed up the power curve was really poor. For example the throttle response would be very poor around 2k to 3k rpm (this turned out to be ignition timing retarding. With all these problems the ecu still read code 55 which means no faults.

Here are some pictures because posts with out pictures tend to be boring.

This is the wiring I used for the knock sensor, and maf sensor. This is rg58 and is shielded, the shielding is grounded.







I also pulled this out of the gas tank. When I would come to a hard stop I could hear something swaying back and forth. once I got home I got under the car but couldn't find anything loose. Deeper inspection revealed that the baffle inside the gas tank had broken loose. I took the fuel pump off and found this baffle loose inside the gas tank . I bent it up while it was inside the tank so I could successfully remove it. Do I need this? I guess when I go auto crossing or mountain cruising I'll be sure my tank is full to ensure the fuel inhalation tube stays submerged.

With the 470k ohm resistor in the car, it runs flawlessly no more bogging no more ignition retarding, and most important no more engine problems. The use of a resistor in the knock wiring is a temporary fix and was originally only used to test my hypothesis that the cts was in fact still operating properly. I have already ordered a new knock sensor and will install it when I have the chance. I'm sure you all know the risks involved in using a resistor instead of a working knock sensor. I'm just kinda pissed that the knock sensor was bad enough to cause problems but not throw a cel or fault in the ecu code, because had the ecu thrown a code 34 I would have been able to quickly asses the issue and wouldn't have wasted all this time, energy, and money replacing/fixing s*** to resolve the problem.