Need help from some knowledgeable individuals!!! We’re lost!!

Riles

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96 cobra purchased two months ago. We figured out quickly it had a issue
MAIN ISSUE- car breaks up at 4K bad.
-Feels sounds like a misfire.
-No power at 4K (falls on its face)
-Crack throttle quick soon as it gets to 4K it breaks up.
-roll into throttle easy you can get it past 4K without it breaking up. That’s it tho any quick movement past 4K it does it!
THINGS WE DID:
1-Imrc delete (verified that is all 100%)
2-Plugs/wires/coils
3-throttle position sensor
4-fuel pump
5-all new gaskets (intake,valve ect)
6- new ecu (old had a chip and was just a mess)
7- all new O2 sensors
8- injectors cleaned and flow tested.. 100% ok
Car was at a shop to try and diagnose it but came up short. I think he was stumped as well (he is a known mustang performance guy. He can make cars fast but I think he wasn’t the best diag guy)
It got to point it kinda was a guessing game on my buddy’s wallet. Pulled car out.
Obviously something is going on and we are at the end of our rope. Will be changing crank sensor as piece of mind since this is the original one.
We do notice one bank is running richer then other. Some data was taken and I will tell him to chime in and give info but we are at a loss.
Only one here have good knowledge of this issue that can guide us on something we could be missing?? Any input is greatly appreciated!!!
 

lwarrior1016

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One bank running richer than the other? Have you replaced the cam position sensor or done anything with the mass airflow sensor?

The chip that was in the car, was it tuned for an aftermarket set of injectors or mass airflow sensor?
 

07GtS197

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Can you post the datalogs? Another member on here recently had a similar problem with his 96 cobra, but his was supercharged. His issue turned out to be the maf was giving funky readings because it was sucking up water from the intercooler. I’m inclined to say your issue is maf related as well.
 
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Riles

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One bank running richer than the other? Have you replaced the cam position sensor or done anything with the mass airflow sensor?

The chip that was in the car, was it tuned for an aftermarket set of injectors or mass airflow sensor?
We were trying to locate the cam sensor last night. Only looked real fast since we only had a few mins by the time we thought to start looking there. as far as chip tuned for aftermarket injectors idk. We are dealing with this blind. Have zero history on this car unfortunately. Mass air he is saying it’s reading correctly but I’m still not sold on that’s ok either so I hear ya in that.
Can you post the datalogs? Another member on here recently had a similar problem with his 96 cobra, but his was supercharged. His issue turned out to be the maf was giving funky readings because it was sucking up water from the intercooler. I’m inclined to say your issue is maf related as well.
I talked to him this am and told him to post data so you guys could see. Told him to give as much Information as he can so everyone can be on the same page. I will let tell him know again to post data info. What should a maf voltage be reading? If working correctly? Thanks in advance
 

Pedrothecobra

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One bank running richer than the other? Have you replaced the cam position sensor or done anything with the mass airflow sensor?

The chip that was in the car, was it tuned for an aftermarket set of injectors or mass airflow sensor?
Have not replaced the Cam sensors or the MAF. From what I can tell watching the data stream recordings my MAF is functiong properly. I have about 5g/s at idle and it ranges through up around 160+ as your pressing the throttle. My LTFT 1 and 2 are pretty high. MY LTFT1 was reading at about 14-20 while accelerating which is strange cause if you go by the way the plugs look my bank 2 is definitely the rich side. My LTFT 2 is close in the same range but not the same. The strange part is when the car reaches 4K from what I can tell both LTFTs are almost at 0 and very close to each other which is strange cause the car is falling apart at this point. I have a lot of recorded data runs from yesterday but I unfortunately cannot get them off my scan tool, I can only view them
 

Pedrothecobra

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Can you post the datalogs? Another member on here recently had a similar problem with his 96 cobra, but his was supercharged. His issue turned out to be the maf was giving funky readings because it was sucking up water from the intercooler. I’m inclined to say your issue is maf related as well.
I can’t extract the data logs from this scan tool I can only view them, the MAF seems to be switching fine from what I can tell rewatching watching the data. Both the G/s and the voltage is doing what it’s supposed to. My question about the MAF at this point would be can that throw off only 1 bank? My bank 2 is definitely rich in comparison to bank 1,( just looking at the plugs
 

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07GtS197

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How old are those plugs? It looks like one is rich and the other lean. Does it have headers? It looks like maybe someone put the sensors on the wrong banks. When you say the maf is switching, does the reading bounce around a lot or steady? How about around 4K rpm’s?
 

95opal

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I see you mentioned coil packs replaced but im gonna say that pack on that bank is NFG.
 

Pedrothecobra

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How old are those plugs? It looks like one is rich and the other lean. Does it have headers? It looks like maybe someone put the sensors on the wrong banks. When you say the maf is switching, does the reading bounce around a lot or steady? How about around 4K rpm’s?
So I’m leaning towards maybe the O2s are switched. When I rewatch the data my LTFT1 is 20% and my LTFT2is around 0-10, I know those numbers are high. I did smoke test and found a few leaks but going off the data my ecu thinks bank one is rich which is not the case. The car does have long tubes and there are extensions on the O2 wires, I’m going to jack the car up and look tonight when I get home. I second guessed myself last night because I drive the car with the O2s unplugged and it didn’t really make a difference
 

95opal

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Your 02s backwards or not wont wipe an entire bank out like that. Have you physically checked the spark from that rich bank?
 

07GtS197

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5 g/sec is a little low. It could be the maf. The O2 sensors are not used at wide open throttle so that eliminates them. Going out on a limb I’d say it’s your maf under reporting airflow.
 

Pedrothecobra

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I just put a gauge on the rail, got 35lbs at idle and it drops when i goose the throttle. I ordered a regulator and it will be here Wednesday. Hopefully this clears it up
 

RICKERMAN

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96 cobra purchased two months ago. We figured out quickly it had a issue
MAIN ISSUE- car breaks up at 4K bad.
-Feels sounds like a misfire.
-No power at 4K (falls on its face)
-Crack throttle quick soon as it gets to 4K it breaks up.
-roll into throttle easy you can get it past 4K without it breaking up. That’s it tho any quick movement past 4K it does it!
THINGS WE DID:
1-Imrc delete (verified that is all 100%)
2-Plugs/wires/coils
3-throttle position sensor
4-fuel pump
5-all new gaskets (intake,valve ect)
6- new ecu (old had a chip and was just a mess)
7- all new O2 sensors
8- injectors cleaned and flow tested.. 100% ok
Car was at a shop to try and diagnose it but came up short. I think he was stumped as well (he is a known mustang performance guy. He can make cars fast but I think he wasn’t the best diag guy)
It got to point it kinda was a guessing game on my buddy’s wallet. Pulled car out.
Obviously something is going on and we are at the end of our rope. Will be changing crank sensor as piece of mind since this is the original one.
We do notice one bank is running richer then other. Some data was taken and I will tell him to chime in and give info but we are at a loss.
Only one here have good knowledge of this issue that can guide us on something we could be missing?? Any input is greatly appreciated!!!
Did you check all hoses for cracks, leaks, or even complete detachment? I had similar issue with my '96 and just looking under the hood I found 1 of 3 hoses from my cold air intake had become detached. New clamp, checked and tightened all, and that was it.
Good luck.
 

D3VST8R96GT

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Can you watch the pressure through the pull? Can you see misfire on the banks?

Def second checking hoses and consider which gaskets were changed and if there could be a vacuum leak.
 
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Riles

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Can you watch the pressure through the pull? Can you see misfire on the banks?

Def second checking hoses and consider which gaskets were changed and if there could be a vacuum leak.
He check fuel psi last night. Apparently it was 35 psi and when he hit it the psi dropped out bad. So that’s where we’re atm. Has all new gaskets ect. He is going over everything angin for sure plus checking more. Will keep thread updated
 

D3VST8R96GT

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Normally a bad fuel pump results in weak/no starts but def seen it them act like that before they failed. More likely a in tank leak if thats the case. Check the fuel filter while youre at it.
 

Monday

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Unplug the MAF before starting. Plug in when running. Any changes?



==========================================

i guess it needs to be read - do the rpm thingy when you do this - if you do this. MAFs been suggested before but i guess it's good cuz you said so
 
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Pedrothecobra

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Found a bad splice coming out of the inertia switch feeding the fuel pump. repaired the splice, my question now is i have 11.5v to 12.5v (while driving). is this normal? car is still breaking up when i lay into it, so i have a new MAF on its way. the body voltage is 13.5 when its running. sound i be seeing more at the pump? it looks like the FP is controlled by the ECU but i cant find anything in the crapy shop manual that i have.
 

07GtS197

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You’ll get some voltage drop through the circuit so I wouldn’t worry about that. Hopefully the maf will fix it.
 

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