Cuts out at 3200 RPM when warm
04-01-2013, 04:43 PM
#1
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Join Date: Apr 2013
Location: South of Dallas
Posts: 28
Cuts out at 3200 RPM when warm
New member here with a problem I hope someone has run into before. I first searched this subject but come up with nothing I havent tried so now I'd like to ask the ZX pro's.
I got an 83ZX with a 79 motor. I swaped the intake to the 83 and relocated the CHTS. The car runs great until it reaches FULL running temperature, then it starts to cut out at 3200 RPM. The best way to describe it is like it has a rev limiter like most modern sports cars. I've tested all the sensors against the FSM specs, both cold and at normal running temperature, and they test good. New connectors on the coolant temp sensor and CHTS. I've drove the car both ways with a manual fuel pressure gauge on the window without even a slight difference in pressures and I've used an in-line spark tester to watch for a weak spark when it acts up... nada! Even put new bushings in the dizzy cause I could feel slight side-to-side movement in the shaft. Problem still persists. I've also checked for wet/corroded connectors at the AFM and TPS. Nada!!! Just what the f#@k am I missing here? I'm about to loose it and go ape sh-- so someone please give me some better ideas even if I DON'T want to hear what they are. Much thanks in advance for all your help!!!
I got an 83ZX with a 79 motor. I swaped the intake to the 83 and relocated the CHTS. The car runs great until it reaches FULL running temperature, then it starts to cut out at 3200 RPM. The best way to describe it is like it has a rev limiter like most modern sports cars. I've tested all the sensors against the FSM specs, both cold and at normal running temperature, and they test good. New connectors on the coolant temp sensor and CHTS. I've drove the car both ways with a manual fuel pressure gauge on the window without even a slight difference in pressures and I've used an in-line spark tester to watch for a weak spark when it acts up... nada! Even put new bushings in the dizzy cause I could feel slight side-to-side movement in the shaft. Problem still persists. I've also checked for wet/corroded connectors at the AFM and TPS. Nada!!! Just what the f#@k am I missing here? I'm about to loose it and go ape sh-- so someone please give me some better ideas even if I DON'T want to hear what they are. Much thanks in advance for all your help!!!
04-01-2013, 06:30 PM
#3
Registered User
Thread Starter
Join Date: Apr 2013
Location: South of Dallas
Posts: 28
Much thanks. I haven't actually tested or replaced it yet (no gas analyzer). I only tested the circuit back when I had cold running and running rich issues. (ran great warm haha) Any other ideas anyone has for me will be greatly appreciated.
I didn't have access to an analyzer but here's what I did then.
This is word for word courtesy of ALLDATA:
1) Disconnect the oxygen sensor pigtail and connect a high-impedance VOM with the positive lead on the pigtail and the negative lead to a good ground.
2) Start the engine and let it warm up, if equipped with an air injection system, disable the system so as not to get false tailpipe readings.
3) Grab the disconnected wire that goes from the oxygen sensor to the ECU with one hand. With the other hand touch the negative battery post or a good ground. The readings should increase on the VOM up to approx. 1 volt and there should be an increase in tailpipe CO.
4) Move your hand from the ground side to the positive post of the battery. Your body will act as a proper resistor and allow a small voltage to the ECU. The VOM reading should fall to almost 0 volts and the CO reading at the tailpipe should go down.
5) If the tailpipe readings acted accordingly but the VOM readings from the oxygen sensor did not go up and down, the sensor is defective.
I got a .675 reading in step 3 and a slow but steady drop in step 4 to about .375 after 90 seconds or so and still dropping slowly.
I didn't have access to an analyzer but here's what I did then.
This is word for word courtesy of ALLDATA:
1) Disconnect the oxygen sensor pigtail and connect a high-impedance VOM with the positive lead on the pigtail and the negative lead to a good ground.
2) Start the engine and let it warm up, if equipped with an air injection system, disable the system so as not to get false tailpipe readings.
3) Grab the disconnected wire that goes from the oxygen sensor to the ECU with one hand. With the other hand touch the negative battery post or a good ground. The readings should increase on the VOM up to approx. 1 volt and there should be an increase in tailpipe CO.
4) Move your hand from the ground side to the positive post of the battery. Your body will act as a proper resistor and allow a small voltage to the ECU. The VOM reading should fall to almost 0 volts and the CO reading at the tailpipe should go down.
5) If the tailpipe readings acted accordingly but the VOM readings from the oxygen sensor did not go up and down, the sensor is defective.
I got a .675 reading in step 3 and a slow but steady drop in step 4 to about .375 after 90 seconds or so and still dropping slowly.
Last edited by Gonzo; 04-01-2013 at 06:52 PM.
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