Mechanics

D21 PICKUP

1987 Nissan Truck

1987 Nissan D21 pickup, 2.4liter, Z24i engine automatic with push button overdrive. 267000km. When I purchased the vehicle about 3 months ago, only issues I noticed were the engine idled a little high, the Park light indicator on the dash display always stayed on regardless of what gear I was in (didn't really feel this was an issue so left alone), and the steady bearing on the driveshaft was shot so I replaced it. Gas milage was fair(about 22miles/gallon CDN) but I thought it could be better.

Then driving to work one day, the truck accelerated very sluggishly and I could barely get it to go 100km/hour. First, I changed the air filter, fuel filter, and plugs with no improvement. I checked for ECM codes and found code 23 and 24 which would reappear even after disconnecting battery in an attempt to reset it. I replaced the O2 sensor and PCV valve. I swapped out the thermastatic air cleaner vacuum motor, air temp sensor, mass air flow sensor, TPS, idle control valve, AB valave, and Fast idle control solenoid with ones I obtained from a local auto wrecker. The truck would now accelerate over 100km/hour but I had an irregular idle and hesitation while accelerating but once I drove about 10 blocks (basically, once it warmed up) it idled and accelerated fine. I also inspected the EGR valve, cleaned the reed valve, and ensured all hoses were intact with no air leaks or blockages.

Then about 1 week later, I noticed I forgot to include a round rubber gasket when installing the replacement mass air flow sensor. So I removed the sensor, inserted the rubber gasket, and re-installed it. Now, the truck wouldn't start. I tried for about 15 minutes and finally got it running but it ran extremely rough, hesitated, wouldn't idle and smoked. I finally gave up and took it to Nissan. They swapped out the injectors claiming one was dumping fuel and the other was spraying irregularily. They tested continuity for shorts and grounds. They also adjusted the idle and tps setting. I picked up the truck and it sounded better but I still needed to pump the peddle to get it started and it would not hold an idle. It was still very sluggish while accelerating and would even cough when it tried to gear up. Code 23 and 24 still appear and now code 12 appeared as well. Nissan said its either the ECM or the Mass air flow sensor but said since nothing changed when trying each of the mass air flow sensors I had provided, they recommended replacing the ECM. So I purchased and installed a remanufactured ECM from Bluestreak the other day and while attempting to start the truck, it turned over for about 10 seconds and was just about to fire up when I noticed fluid coming out of the ECM and smoke was emmiting from it as well. Very frustrated, I checked for codes and found code 23 and code 24 again.

Nissan says its a bad ECM but why are these same codes showing on the new ECM as well after all I have done? I am thinking a short is coming back to the computer from a connector, bad wire, relay or sensor but why didn't Nissan detect this from the continuity tests? What can I do? I have spent over $1000 on this truck already so would greatly appreciate any feed back. Thanks very much.
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Stumpt
July 14, 2007.




Well if the new ecm smoked and the old one didnt I would try another, but not a bluestreak. Double check th ewires at the MAF to be sure one isnt pushed out or not getting a good connection since it ran then when the o'ring was installed wouldnt. I would take it back to Nissan and ask why after all the diagnostic and parts it still runs like this. Sounds like they might have mis-diagnosed it in the first place
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Tiny
Jack42
Jul 15, 2007.
I will check the MAF wiring. It does seem odd the truck started without pumping the peddle and ran decent at least (before I removed and reinstalled the MAF to replace the o-ring gasket). Other than the rough idle when cold. I am pretty sure the orginal computer needed to be replaced anyways and was likley part of the issue but would assume it had already experienced the same damage as the new one I put in since it displayed the same codes from the beginning (before I did any work on the vehicle) If the MAF wiring is okay, is it possible both of my MAF's are no good and getting a new one may get me going again? If so, what explains the code 23 and 24 (Is it right that 23 = idle switch, 24 = TPS which are both in the same sensor component. Some sources show code 24 = neutral/park safety switch. Is this on the transmission?) Thanks again

Tiny
Stumpt
Jul 15, 2007.
I admit this is over my head but wondering if it is possible the Main Relay could cause these problems? Could it be working enough to power the fuel pump when the key is turned on but doing something faulty after that? Hence shorting the ecm? And explain why the peddle needs to be pumped in order to start the engine? Thanks again

Tiny
Stumpt
Jul 15, 2007.
It sounds like it is getting too much fuel if the pedal has to be " pumped" to get enough air in it to start. The park/neutral switch is on the trans and is most likely why the dash indicator showed park no matter what gear it is in. Might have to start doinf pin-to-pin wiring checks for the TPS circuit to the ECM

Tiny
Jack42
Jul 16, 2007.
Wiring appears fine but problem is worse now. I got my old ecu back, put it back in and the truck won't start now unless I add fuel into the throttle body. The pump powers up when I turn the key on and I checked for fuel pressure while turning the engine over. Fuel does pump out when I disconnected the hose on the 'out' side of the fuel filter. Did I possibly create an air lock or something by pumping the pedal in an attempt to start it? It started before with this ecu but I had to pump it and it wouldn't hold an idle.

Tiny
Stumpt
Jul 19, 2007.
I doubt you created an air lock. I should have asked sooner, is this FI or comp controlled carb?

Tiny
Jack42
Jul 20, 2007.
Referred to as tbi? Does that help?

Tiny
Stumpt
Jul 21, 2007.
If you have to add fuel to the tbi, then it sounds like the injectors arent " hitting" or getting signal to spray fuel. Check for power to the injector/injectors

Tiny
Jack42
Jul 22, 2007.
Get rid of the codes 1st. See n think what the ECM thought the problems are. Both 23, 24, 12 are simple code. Either they lose pwr & grd or losing 5 volt refrence thats Y the code keep popping up!. Voltage drop from ECM all the way to the sensor key on engine off.

Tiny
Kin chan
Jul 23, 2007.
I agree with you 100%. I want to get rid of the codes. Nissan won't elaborate on the details of these codes and tell me the problem is the ECM or MAF yet the codes don't suggest it. That's why I tried changing the ECM thinking it was a bad ECM throwing faulty codes.
I checked the wiring to the injectors. I tried unplugging the harness connection for wires from the injectors and TPS to the ECM and checked the codes again. I still get code 24, code 23 is gone, but did get code 43(injector circuit open) When I reconnect the harness, code 23 returns but code 43 goes away. Wouldn't that indicate the injector circuit closed? If this is the case, wiring pertaining to the injector should be fine, not?

Tiny
Stumpt
Jul 23, 2007.

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