Bringing this m20 back to life

[mbonanni]

Bringing this m20 back to life *misfire*

I didnt switch it with a new one but I did try a different sensor and it didnt help with the idle.

[audiquattrot]

Did you replace both temp sensors or just the coolant one? Change the other one next to it if you haven't already done so

[mbonanni]

Bringing this m20 back to life *misfire*

I've replaced the o2 sensor and now the car runs without any CEL, however it still idles rough.

Ive replaced:
Spark plugs
Cap
Rotor
O2 sensor
O2 heater/fuel pump relay
Tried different plug wires
Tried different injectors
Looked for vacuum leaks
Spliced c191 connector
Replaced Engine ground
Swapped ECU
Fuel pump (used)

Car idles around 550-600rpm but seems to either miss or have a vacuum leak. I am also blowing fuse #9 instantly upon start up, which is fuel delivery/idle system. I thought maybe the fuel pump but When I revv it up it runs smooth through the rpms, does not stutter, and when it gets back down it surges a little then will find its idle back at 550-600rpm. Under load a bad fuel pump would cause a stutter right? Could low fuel pressure result in bad idle but run smoothly up the rpms?

[mbonanni]

Bringing this m20 back to life *misfire*

Just switched the relay with a new one. Fuse 9 blew even quicker this time. So CEL and code 1264, new o2 heater relay, blowing fuse 9.... Waiting on the new o2 sensor

[mbonanni]

Bringing this m20 back to life *misfire*

I believe I tried switching the injectors, but if the new o2 and relay doesn't help then I will try it. I have felt around to see if that hose was disconnected but felt fine. Ive read many people having issues with this so I will make sure to check it again. Thanks

[ahlem]

You can switch the injector to another cylinder and see if the miss follows it. Did you check to se if your power brake hose might be the source of a vacuum leak?

[mbonanni]

I finally fixed my heater valve and got the car back up and running again, still runs a little rough at idle. I am not driving the car but it runs rough at idle and hesitates when giving it throttle. I reset the CEL codes and it would stay off for a little, but once I give it a little throttle the light flashes then stays on, this time it is code 1264, and fuse #9 is blowing. I ordered a new o2 sensor and relay in hopes of fixing the issue.

[mbonanni]

Deleted the c191 plug by splicing in the injector harness, seems to run smoother, but i think i still have a miss in cylinder 2. Im guessing its the injector, any suggestions?

Also my CEL is still on and throwing code 1223. I let the car get to operating temp and it ran the same. Drove the car around the block and the light would flash on and off. I was only in the neighborhood so I only got up to 25 or so.

Also my heater valve is leaking.

[mbonanni]

So I ran to autozone and grabbed one of their sensors to see if I could get the code to disappear., installed a new one and it is still there I know these sensors aren't all that great, but could this sensor be the issue to my rough idle? I let the car get to operating temperature, restarted it etc and the code never went away. The car also does not react if I disconnect the sensor.

[mbonanni]

Bringing this m20 back to life *misfire*

New cap and rotor are on but still have a misfire. I think it is only in cylinder #2 but it is hard to tell.

Check engine light is on and trowing code 1223, coolant temp sensor. Could this be effecting stuff?

[mbonanni]

Bringing this m20 back to life *misfire*

Well, removed the harness and cleaned it up and then roughed the surface up. Also tried to clean the injectors pins and it didn't help. They didnt look bad to begin with.

Guess time to check the cap and rotor. I'm probably going to try some high performance bav auto wires and a diff cap

Edit: Yup cap and rotor are shot. Chips and all the posts are black. I cleaned it off best I could and managed to get one more cylinder firing. So 4/6. Runs a lot smoother as well. Will be ordering new stuff tonight.

[ForcedFirebird]

Yes I do have that connector, but I am a little confused as what you're saying. Because of the way that harness is wired in banks its likely that it corroded somewhere and has bad connections? I'll pull it when I get home and inspect it, however I've tested to make sure the injectors are firing and they all are. I cannot tell if they're firing while its running but I know they are while cranking.

Why would the harness having different banks mean that it isnt likely the cap/rotor is the issue here.

Yes, the connector goes bad. Bet the terminals are green.

The cap/rotor just moves the spark from the coil from one cyl to the next - it doesn't have "banks", but the injectors do...

[mbonanni]

Bringing this m20 back to life *misfire*

Yes I do have that connector, but I am a little confused as what you're saying. Because of the way that harness is wired in banks its likely that it corroded somewhere and has bad connections? I'll pull it when I get home and inspect it, however I've tested to make sure the injectors are firing and they all are. I cannot tell if they're firing while its running but I know they are while cranking.

Why would the harness having different banks mean that it isnt likely the cap/rotor is the issue here.

[ForcedFirebird]

Being a late model, you probably have the round injector harness connector under the TB/manifold. That connector has a habit of corroding and kills half the injectors, or messes with the coolant temp sensor (in that same plug).

In that plug, there's a temp gauge wire, temp sensor wire(s), a ground for each injector (ECU grounds injector to energize, they are always hot), and two battery positive - one for each bank - ie injectors 2,4,6 and 1,3,5. With m20 having a distributor, one whole bank is unlikely to have ignition as the culprit.

[mbonanni]

Bringing this m20 back to life *misfire*

Awesome, thanks guys. I'm out in Vegas for a little vacation so once I get back I'll make sure to order up one of those spark testers and peep the condition of the cap and rotor.