High idle after driving and code 33
Thread Starter
Intermediate
Joined: Jan 2009
Posts: 46
Likes: 0
From: Fredericksburg Virginia
High idle after driving and code 33
New 86 owner here! Picked up the vet last March after it sat for several months from PO. I've used this forum a lot ot get her on the road again. Thanks for all the past help.
I joined to post these problems:
1. At startup idle is fine, during and after a drive idle slowly creeps up to 2300 RPM in neutral or park. Shut down and restart, idle is back to normal? While driving, engine occasionally bogs and when braking increases idle which doesn't come back down.
2. I have a persistant code 33, steps I've taken below.
PO had removed the SES bulb which has been throwing a code 33 since day one, within 5 seconds of start up. It never goes away and I am disconnecting the neg battery terminal to clear codes.
Tried a good MAF from a reputable vette shop and same code.
Cleaned TB, AIC, reset min. idle and TPS to spec.
New fuel filter and PCV after running two cans of 44k.
New MAF relays (both)
New safety neutral swith (back up lights weren't working)
Voltage to MAF checks out.
Ohm reading on injectors all at 63
The only MOD is aftermarket Borla exhaust.
What am I missing?
Thanks!
I joined to post these problems:
1. At startup idle is fine, during and after a drive idle slowly creeps up to 2300 RPM in neutral or park. Shut down and restart, idle is back to normal? While driving, engine occasionally bogs and when braking increases idle which doesn't come back down.
2. I have a persistant code 33, steps I've taken below.
PO had removed the SES bulb which has been throwing a code 33 since day one, within 5 seconds of start up. It never goes away and I am disconnecting the neg battery terminal to clear codes.
Tried a good MAF from a reputable vette shop and same code.
Cleaned TB, AIC, reset min. idle and TPS to spec.
New fuel filter and PCV after running two cans of 44k.
New MAF relays (both)
New safety neutral swith (back up lights weren't working)
Voltage to MAF checks out.
Ohm reading on injectors all at 63
The only MOD is aftermarket Borla exhaust.
What am I missing?
Thanks!
Thread Starter
Intermediate
Joined: Jan 2009
Posts: 46
Likes: 0
From: Fredericksburg Virginia
Forgot to mention on the 86
Mileage is 185000, ECM is tan in color?
I drove it again earlier today and same problem with the idle going higher and higher! Shut it off and idle reset to normal.
Thanks,
Mark
I drove it again earlier today and same problem with the idle going higher and higher! Shut it off and idle reset to normal.
Thanks,
Mark
Instructor
Joined: Dec 2004
Posts: 176
Likes: 0
From: Oakland CA
I had a similar issue which turned out to be a bad tps. It would appear to be fine when the car was sitting with the engine off. I backprobed the connector to the ECU to get a real time voltage reading while driving. When it set the fault and the idle increased I saw the tps voltage increase which is how I finally found the problem. To confirm it, I checked the voltage at the tps with the ignition on while gently torquing on the tps body which cause big voltage fluctuations. Good luck.
Thread Starter
Intermediate
Joined: Jan 2009
Posts: 46
Likes: 0
From: Fredericksburg Virginia
Thanks Rat, I'll try testing the TPS at different RPM's. The voltage has moved around a bit and it did throw a code 22 (high TPS voltage) twice the other day after doing some cleaning to the TB,etc. (thought I had maybe bumped it) It had changed form the .54 to
.70 so I did the reset on the Min. idle and got the TPS back to .54. Still throwing code 33 and having the idle issue but maybe the TPS is the problem.
I was thinking O2 sensor or coolant temp. sensor. By the way I did swap the 180 thermostat for a 160, maybe that has something to do with it?
.70 so I did the reset on the Min. idle and got the TPS back to .54. Still throwing code 33 and having the idle issue but maybe the TPS is the problem.
I was thinking O2 sensor or coolant temp. sensor. By the way I did swap the 180 thermostat for a 160, maybe that has something to do with it?
Instructor
Joined: Dec 2004
Posts: 176
Likes: 0
From: Oakland CA
My experience was that the old tps seemed sensitive to adjust. It took precise fiddling to get the voltage where I wanted it. The replacement I installed is rock solid.
I'm not sure but I think for a daily driver, 160 degrees is too cold. The ECU may not go into closed loop for a long time and may open again if you are cruising at freeway speeds. I used to have a 180 degree 'stat which would give a temperature indication of 178 or so on the freeway. I swapped it for a stock 195 and flushed the system really thoroughly. It runs great.
I'm not sure but I think for a daily driver, 160 degrees is too cold. The ECU may not go into closed loop for a long time and may open again if you are cruising at freeway speeds. I used to have a 180 degree 'stat which would give a temperature indication of 178 or so on the freeway. I swapped it for a stock 195 and flushed the system really thoroughly. It runs great.
Thread Starter
Intermediate
Joined: Jan 2009
Posts: 46
Likes: 0
From: Fredericksburg Virginia
Problem solved
Thanks to RAT for the suggestions and Agent 86 for posting the code 33 flow chart.
Turns out the IAC was bad which, when replaced, fixed the bogging and idle issues. The codee 33 was being caused by bad contact in the MAF sensor harness.
Pulling of the MAF sensor connector I noticed that 3 of the female connections had been spread out fairly wide, so I pinched them down, reconnected, and the code 33 went away.
All is well now except I'm curious why my oil preassure is reading zero at idle, goes higher while under load.
Thanks again for the help!
Mark in Virginia
Turns out the IAC was bad which, when replaced, fixed the bogging and idle issues. The codee 33 was being caused by bad contact in the MAF sensor harness.
Pulling of the MAF sensor connector I noticed that 3 of the female connections had been spread out fairly wide, so I pinched them down, reconnected, and the code 33 went away.
All is well now except I'm curious why my oil preassure is reading zero at idle, goes higher while under load.
Thanks again for the help!
Mark in Virginia
