Hello guys, so I stumbled across this problem and it's been a riddle, since I just took the car to my local mechanic and we were unable to identify the problem.
Here's what's going on: The CHECK ENGINE light is ON and after a couple of minutes driving, the RPM needle goes crazy and the car starts to shake a lot (surging). The exhaust even pops sometimes (backfire?) and all of this happens only while driving, never during idle. Speaking of idle, after a short drive the RPM won't fluctuate at idle, but will hang at a bit over 1000 RPM's and the engine sounds a bit weird. When the car is cold it idles fine (around 650 RPM's). Also, the car even died while I was driving, even though it was a single time and at a low speed. Anyway, it shakes A LOT (as you can see in the video). Spark plug/spark plug wires are good, fuel injectors are also good. We put a new ICM but the problem persists.
I was thinking maybe IAC? MAF? something on the PCM? Thanks in advance, here's the link to the video:
Did you use a scanner or did you use the jumper wire method instead?? If it was a scanner,use the jumper wire method.The link at the end of this paragraph details how to run the tests & how/where to connect the jumper wire.You should at least get the "system pass" (111) code,if the test initiated & ran,but no codes were present.If you cant get the test to begin at all,a wiring or ecu issue could be present.This can cause the test to not initiate when using a scanner.This is why the jumper wire method is oftentimes better,just in case something is amiss like I mentioned above.So go ahead & try the diy method now.Connect the jumper wire between the STI terminal and the SIGNAL RETURN terminal then turn the key on & the test should begin.If the test runs,count the flashes,write the codes down then post them.If you turn the key on & nothing happens,move the jumper wire from the SIGNAL RETURN terminal to the negative battery terminal then try to initiate the test again.It should work now (This connection method is shown in the diagram below at the bottom right corner) If the test doesn't run when connected between the STI and SIGRTN terminal,but it runs when connected between the STI & neg battery terminal, the wiring and ecu need to be checked.
*edit*
I just read where you have a check engine light on. Are you sure you stuck it in the right hole? The port under the dash isn’t hooked up to anything. There’s another under the hood.
Yes, but I think I found out the problem, my computer is kinda "messy". Is it possible that the computer can cause this? Cause everything else seems fine. Think I gonna get a new one.
you could theoretically jumper pin 46 to 48 and then 17 through a multimeter or test light to battery positive to pull codes. Again this is for a '90 computer, I doubt the actual pinout changed for mass air cars but I cant 100% confirm.
The following pics detail which o2 harness is for which ECU type.The only difference between the two harness types is the purple/yellow looped wires terminal position.If you are using the incorrect harness for your application,you can either buy the correct harness or you can simply modify the harness by moving one end of the looped wire from its current terminal position to the correct terminal position.IOW - you pull one end of the looped wire out of its terminal (after disengaging & removing the plugs plastic locking tab & pressing down on the wire pinout locking barb) then you move that wire end to the correct terminal & reinsert the locking tab.Further info can be posted for this process if needed,but for now the pic shown below will help you id which harness you've got.If you're running a A9L ECU now,you'll also need to be running a A9L o2 harness too.If you are running both of these currently,you should be safe to go ahead and attempt the code 67 bypass listed a few posts back so that you can then attempt to run the KOER test.
BTW - the harness plug shown in the pic below is located at the end of the o2 sensor harness,opposite the end that actually plugs into the o2 sensors and the low oil sensor. You can see how on the manual (A9L) harness plug,the wire loops from the top right terminal to the bottom right terminal & on the aod (A9P) harness plug,the wire loops from the bottom right terminal to the terminal directly one pin to the left of it.So you can see which end of that wire changed positions between the manual harness vs the aod harness & eventhough its not visible on the harness in the picture,the aod harness has a rubber plug in the terminal position on the top right that has to be drilled out if you were to have to relocate the looped wire from the aod terminal position to the manual terminal position.You can cross that bridge if you get there though.I just wanted to elaborate on it so that you or anyone else whom might need this info will have it.Hopefully youve got the correct harness already.
The following pics detail which o2 harness is for which ECU type.The only difference between the two harness types is the purple/yellow looped wires terminal position.If you are using the incorrect harness for your application,you can either buy the correct harness or you can simply modify the harness by moving one end of the looped wire from its current terminal position to the correct terminal position.IOW - you pull one end of the looped wire out of its terminal (after disengaging & removing the plugs plastic locking tab & pressing down on the wire pinout locking barb) then you move that wire end to the correct terminal & reinsert the locking tab.Further info can be posted for this process if needed,but for now the pic shown below will help you id which harness you've got.If you're running a A9L ECU now,you'll also need to be running a A9L o2 harness too.If you are running both of these currently,you should be safe to go ahead and attempt the code 67 bypass listed a few posts back so that you can then attempt to run the KOER test.
BTW - the harness plug shown in the pic below is located at the end of the o2 sensor harness,opposite the end that actually plugs into the o2 sensors and the low oil sensor. You can see how on the manual (A9L) harness plug,the wire loops from the top right terminal to the bottom right terminal & on the aod (A9P) harness plug,the wire loops from the bottom right terminal to the terminal directly one pin to the left of it.So you can see which end of that wire changed positions between the manual harness vs the aod harness & eventhough its not visible on the harness in the picture,the aod harness has a rubber plug in the terminal position on the top right that has to be drilled out if you were to have to relocate the looped wire from the aod terminal position to the manual terminal position.You can cross that bridge if you get there though.I just wanted to elaborate on it so that you or anyone else whom might need this info will have it.Hopefully youve got the correct harness already.
Thanks again for this detailed info. I will have to check, but I definitely have the A9L computer and can say with almost 100 certainty that the o2 is for the A9L...since I bought the car with a manual and didn’t change the o2 when I did the swap.
As for drivability - with the manual it would stall at idle with the AC on, no power until 3rd gear and mad revving in 1st while going nowhere, clunking along in 2nd, and then 5th was just dead. The AOD is like a rocket ship.
No I think I need to replace the o2 sensor on the driver side since it smells like crazy gas.
Were they dry? Looks somewhat rich maybe. Carbon.
Could be quite a few things I guess. Maybe the 24# injectors and MAF combo. Vacuum leak? Is there a commuter chip sticking out of your ecu? That green thing is the chip.
Yep, they were dry. And yes, there is a computer chip. I am actually going to try and call the shop that turned it to see if I can get the specs on the tune*
*Bought the car in 2014 with pretty much everything already done to it. In the paperwork, there is a receipt for “Mustang Tune”. I know the guy before me had all the work done to it and gave me all the receipts.
If it wasnt for the fact that it only gets opened by the ecu during part throttle & cruise conditions,an addition of an egr valve might help reduce some of those exhaust gases,since they would get rerouted back into the engine by the ecu and reburned. This causes the combustion chamber to run cooler + the ecu leans the fuel trim and advances timing also when the egr valve is open,but it wouldn't help at all outside of those running modes,like during idle,etc.Plus the emissions items have been turned off in your tune,which means you would have to pay a tuner to turn the egr valve back on + the wiring for the EVP sensor & EVR solenoid has likely been removed from the main harness too.So all of this isnt worth the trouble.
I pretty much have determined there is no charcoal canister, there’s no cats, and no EGR.
I was able to get a hold of the shop today and guy basically said “yeah, we tuned the MAF for 24# injectors but I can’t remember any other specifics. You should ditch the POS Ford computer and get a Holley.”
Sooooo, at this point, what is the best recommendation (to get rid of the gas smell so my wife will drive with me and I can wear something other than workout clothes and my flight suit)?
The chip can only be read by the person who writes it. They can erase what’s on it and write another though.
I’m not sure that Bama etc would let you reuse your chip, they’d probably make you buy one from them. I wouldn’t do that anyway though. You want a tune based on live or recorded data. Not a tune based on a list of modifications.
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