Question : Misfire is driving me completely bonkers, help!

[3rdgen8284]

Hey guys,

I still have a problem with misfiring. I have replaced the following with new/remanufactured

Injectors
Plugs
Leads
Cap
Rotor arm
Coil pack
Fuel pump
fuel filter
Fuel feed line
Fuel return line
Fuel tank
All vacuum pipes & lines
Pacesetter headers
K&N filter with custom ducting which includes stock MAF
IAT sensor
195 stat
16lbs rad cap

I have removed the following

EGR complete system
Air/smog pump and all associated piping
Carbon canister and all associated pipes wiring
Cat (replaced with straight through)

The following are original NOT REPLACED parts

Fuel pressure regulator
Injectors harness
O2 sensor
MAF
Coolant temp sensor

I retimed it to 10BTDC (OEM) yesterday as it was about 5 degrees out and since then it's been misfiring like crazy. And yes I did it at operating temperature so the lack of IAT sensor readings wouldn't affect it.

Battery has been disconnected for a good hour to clear any codes and once running it gives me no codes at all despite not having an EGR.

Anyone got any idea why I have a random misfire? It's driving me absolutely mental. And another thing is that the temperature on the gauge never gets higher than just over 100F, despite the fan citing in and out and the area around the sensor being 89C. What's that all about?!

Listen to this but make sure you have your bass turned up so you can hear the 'popping'....

https://youtu.be/aLS3f7y-8a4

[3rdgen8284]

Wow! What a response

[LeftVentricle]

Wow! What a response

This forum has been quite slow recently. I'm not at all surprised.

This is going to sound incredibly elementary, but have you checked to see if the plug leads are going to the correct cylinders? I had #2 and #6 crossed recently, and it missed like mad. Swapped them to the correct holes, and all was well.

[3rdgen8284]

Surely it would miss cold or warm though?

[Purple pit]

The fan is turning on and off? Coolant temp sensor would do that. Had that go bad on me along with a major problem caused by aftermarket coils(Accel). Be warned, there are two firing orders running around on the web. One is right and the other wrong. List what you have and we can go from there.
My misfires seemed to come and go. One day it's just fine the next it was running like crap.

[3rdgen8284]

Yes cooling fan is cutting in and out. The 2.8 MPFI has three coolant sensors though doesn't it? Ok i'm working on this firing order;

WINDSHIELD

5 6
3 4
1 2

COOLING FAN

This runs fine when cold, and misses like hell when its warm.

[Purple pit]

It would be near the water neck. Didn't read you name and was thinking that you had a FWD. There are changes between the FWD and RWD 2.8/3.1's that I don't know about.

[Purple pit]

Did you get a new coolant temperature sensor yet?

[3rdgen8284]

Sorry for delay, for some reason this forum doesn't send me an email when someone posts on the threads!

I wasn't convinced the info I'd been given about the cylinder numbers was correct. It wasn't! I'd set No. 2 up as No.1. So I dismantled the lot and re-connected the wires and re-timed it again! It ran MUCH better but I'm still getting a temp variation between the front and the back of the motor.

The rear sensor is at about 102C and the front sensors are reading 80C, so I'm pretty sure the rear emergency fan override sensor is the one triggering the fan. Also the motor is idling at 1100RPM instead of 800 so I'm wondering hat is causing that. There are no vacuum leaks so I'm a bit lost with it but it's driving me nuts!