SR swap mystery problem-You'll have to be pretty smart for this one....

[Spdrules5]

Blacktop SR20DET with 5spd into 89 coupe (auto to man conversion done).

Car will barely start, then runs on two cylinders(the middle two only). I unplug the MAF and it makes no difference, BUT, the RPM's WILL raise over 2500 rpm no problem.

I have:-I replaced MAF with known good one--no change-I replaced ECU with known good one--no change-I replaced CAS with known good one--no change-I chkd' continuity between sensor plugs and blue ECU plug--all seem good-I replaced wire harness with known good one--NO change!-I pulled valve cover and put CAS 180* off--would not start

I have pulled each coil pack one at a time and checked:-spark across gap--all fire-constant 12v to top of coils--all good-ground--all good-signal--something measured as it fired-all gapped at 0.032

All grounds are attached in approprite places

I am at a total loss. Please help.

Thanks in advance

[Spdrules5]

Needed to add:

Stock injectors were all serviced at RC Engineering before new orings and seals were installed and put back in fuel rail.

[navysnail]

are they all pulsing, and you dont have any of the injector leads mixed up do you

[Spdrules5]

I guess I would have to pull the whole fuel rail out to see if they are all spraying, huh?

[navysnail]

no, just hook up a noid light to it, the GM one works if leu of a nissan one. i dont think you could pull the rail and pressurize the system with out them shooting out of the rail from the pressure

also, make sure you didnt mix the injector leads up so say, #2 wire was hooked up to #3 injector and so on

[s13sr20chris]

mixing up redtop and blacktop ecm and harness will kill two cyls. what number is on you ecm? its a two digit number. i think the 62 is the m/t redtop model that i have.

[Spdrules5]

It might be a redtop harness with my blacktop. How do I check?How important is the lower harness? I am using my auto '89 KA harness.

Also, I put a '98 180SX blacktop ECU and the same wire harness, with the same outcome. first and last cylinders don't seem to be running, although they have spark.Sounds like timing, but CAS has been installed both ways and I have moved the CAS during cranking and running with no change.

[s13sr20chris]

you used a 180sx blacktop harness with the 180sx blactop ecm? if that was a running combo and did not fix yours then this does not apply.

[180fan]

98 180sx ecu's do not have the same pinouts as the 91-96 ecus. If you've used the 98 harness for the 98 ecu and still no luck after the redtop ecu/harness combo, it's probably not it. If you're not getting combustion at 1 and 4, have you checked the spark plugs for sparking? If it's 1 and 4, it could be your ignitor, since the chance of 2 coil packs going out at the same time is pretty slim or it could be your cas. Try a different cas as the last resort since it's a bit of a chore to line everything up TDC.

Have you checked the injectors? They're supposed to be around 12 or 14 ohms. Check them for clicking also when your motor's running and pull the injector plug while the motor's running to double check to see if the injector's functioning, that is if you're getting spark.

EDIT: just saw you're getting spark on all 4. Then it's gotta be fuel, unless you've got something severe like blown up pistons or shot valves.

[Spdrules5]

Thanks for all the input.

New update:

I pulled the fuel inj. out one by one and re-installed them. I know have 3 cylinders working. One of the fuel inj. aren't clicking open/close. I moved it to another cylinder, then that cylinder didn't work but the first one did.Fuel injectors were just serviced by RC Engineering. They flowed all the inj. and gave spray rates and such on paper. I'll take the one back and see if they will do something.

**I can still unplug my MAF and it won't affect driveability. One problem at a time I guess.

[s13sr20chris]

is the one thats not working getting a signal?

[Spdrules5]

Yes on the signal. RC said the pintle was stuck closed. They fixed it and I will install as soon as I am done with work.

**My MAF still performs no function on my car. I have replaced it with a known good one. Same problem. The engine DOES rev way past 2500 rpm. There is no difference with or without MAF, any MAF. The 3 wires are correct into the ECU with power and ground good.Any ideas???

[180fan]

Check the wiring for the mafs. http://sr20det.nismo.org/srtech.htm

that should get you started with the pinouts check out the pins for the mafs and check the harness. If the harness checks out, check the actual connection between the harness plug and the mafs.

[Spdrules5]

I printed the link you gave and checked continuity between all MAF wires and their respective places(number) going into the ECU on the blue plug. All good their, same problem.What about the sheilding off the MAF wires?

The ECU is a 62. If it is programmed for a Z32 MAF, would that make a difference as far as the engine not responding to the MAf being plugged in or not and run normally?

[180fan]

don't see why it wouldn't respond to a MAFS if it's been programmed to take it. Just that if the MAFS is unplugged, you shouldn't be able to rev past 2500. The shielded MAFS wires are pretty important to have. From what I understand, the voltages that come from the MAFS is pretty low and can get skewed on it's way from the MAFs to the ECU. So I reckon it's a pretty good idea to use shielded wires for the MAFS.

[Spdrules5]

I agree. Since my car is on jack stands(very securely) I run through the gears way past 2500(without MAFS connected!). My car makes boost, my BOV is loud. I don't understand why this gremlin won't show itself.

I'm sure once I put the car on the road and put a load on the motor, things might be different. Definetely not as good as the car should be.

I'm thinking about runing my own wires from MAF straight to ECU plug.

[llamabeta]

I'm sure once I put the car on the road and put a load on the motor, things might be different. Definetely not as good as the car should be.

Absolutely.

I'm thinking about runing my own wires from MAF straight to ECU plug.

Be sure to shield those properly. As mentioned above they are interferred with easily.

[Spdrules5]

I ran a brandnew set of wires from MAF to ECU and no difference with MAF plugged in or not when I revved the motor to way over 2500 rpm's. It seems to be running rich(whiffs of black smoke out the exhaust when revving).

Would the O2 sensor play any part of that if it is not sending or receiving signal, ground or something?

How would the coolant temp sensor or TPS interfere with this problem?

PLEASE HELP I'VE FRIED MY BRAIN

[s13sr20chris]

coolant temp tells the ecm to richen up with colder temps. higher resistance(like open) will default to something like -30 degrees.

[Spdrules5]

Which sensor or wires is the coolant sensor by the throttle body? The single wire or the plug next to it?How do I tell if it is bad? Can I run a multimeter on it? What am I checking for?What other sensors can I check with the multimeter? O2?

[s13sr20chris]

the two wire is the ect. you can check it with a meter but i forget the resistance it should have.