Almost 2 years after buying my Cobra, I finally got to take it to the track. Unfortunately, the results will very disappointing and I’m convinced there is a problem sucking power out of this car somewhere. Finding what is causing this is going to be the mission and I’m coming here for help.
First…a little background: Car has 79,xxx miles on it and a somewhat unknown past with several owners. It has the following go-fast mods: 4.56’s, Longtubes, Off-road X, Pullies, Cold-Air w/ MAF, and an old Autologic chip put in by Lidio Iacobelli at Automotive Performance several years ago. The rest can be seen in my signature. The guy I bought it from knew nothing about performance and had taken it to a mechanic before he sold it to have a tune-up done with plugs/wires, all fluid and filter changes, etc… I have the paperwork on this. Other mods were from previous owners.
Now…I came from a H/C/I 94 GT that ran 12.7 @ 110…so my goal was to buy a 4V SN95 that would be somewhat comparable speedwise, but better driveability and cruiser. I thought I found it with this car and although I knew it would be a little slower than the GT…with the mods it has, I figured low 13’s @ 105-107mph would be the norm and with a little work I could crack the 12’s.
Well…I knew something wasn’t right after my first pass went 14.1 @ 101.2. I made about 5 more passes throughout the evening and the best I could muster was a 13.9 @ 101.8. I was shifting around 7k at each run. Sometimes trying 7200rpm, sometimes 6800rpm…no difference. The ET does not worry me, the track was prepped like crap and my NIttos were not sticky no matter how much I heated them up. The MPH is where I am worried though, as it indicates I could be 30hp or more low? Especially with 4.56 gears and Longtubes…not even hitting 102mph is indicating a big problem to me.
Now…it was pretty warm out…mid-to-low 80’s…and calculated DA was around 2500ft, so I could see that taking some power out…but even corrected to sea level it was not hitting 13.5 @ 105 on my best run. The consistency was weird…here were all the trap speeds:
101.22
101.23
101.77
101.77
101.35
101.54
The 1/8th miles were all around 79.5 It’s almost as if no matter how I drove it, it always was within a 0.5mph of each other…all throughout the evening and the temps probably dropped 10-15 degrees by the end of the night. I even ran the car hot and cold. It’s almost as if the car was in a sort of limp mode and always limiting to the same power.
I am still somewhat new to the 4V world, so I need to learn what the problem areas could be. Here is the short list off the top of my head:
- IMRC’s (don’t know too much about these…can they cause big power loss?)
- Chip (I didn’t pull it out to see if there was a difference…but can’t see it causing a power loss. I spoke to Lidio and he said it advances timing and spark tables and little things like that)
- MAF – This is in the inner fender…haven’t even looked at, but what should I be looking for?
- Tune-Up – Like I said, it had this done, but I could double-check everything since God knows what they put in there.
- Motor – Hope not here…but a compression test would be my thought.
The only other thought I have is a fuel issue. I say this for two reasons:
1) It has a very bad problem of not starting….cranks forever and I think it is a fuel starvation problem. Gets much much worse when hot too.
2) I’ve noticed when I get under a ¼ tank of gas and give it WOT, it sometimes hesitate and seem to jerk or miss a little. Only happens when low on gas though.
I could start by replacing the filter (although this was supposedly done) and then check the fuel pump, but that's all I can think of.
Any thoughts or advice on where else I should start looking? I want to avoid throwing money at it and will probably only be taking it to the track one more time this year in September. If I don’t hit low 13’s with at least 105mph, it will be a very long winter.
Thanks
First…a little background: Car has 79,xxx miles on it and a somewhat unknown past with several owners. It has the following go-fast mods: 4.56’s, Longtubes, Off-road X, Pullies, Cold-Air w/ MAF, and an old Autologic chip put in by Lidio Iacobelli at Automotive Performance several years ago. The rest can be seen in my signature. The guy I bought it from knew nothing about performance and had taken it to a mechanic before he sold it to have a tune-up done with plugs/wires, all fluid and filter changes, etc… I have the paperwork on this. Other mods were from previous owners.
Now…I came from a H/C/I 94 GT that ran 12.7 @ 110…so my goal was to buy a 4V SN95 that would be somewhat comparable speedwise, but better driveability and cruiser. I thought I found it with this car and although I knew it would be a little slower than the GT…with the mods it has, I figured low 13’s @ 105-107mph would be the norm and with a little work I could crack the 12’s.
Well…I knew something wasn’t right after my first pass went 14.1 @ 101.2. I made about 5 more passes throughout the evening and the best I could muster was a 13.9 @ 101.8. I was shifting around 7k at each run. Sometimes trying 7200rpm, sometimes 6800rpm…no difference. The ET does not worry me, the track was prepped like crap and my NIttos were not sticky no matter how much I heated them up. The MPH is where I am worried though, as it indicates I could be 30hp or more low? Especially with 4.56 gears and Longtubes…not even hitting 102mph is indicating a big problem to me.
Now…it was pretty warm out…mid-to-low 80’s…and calculated DA was around 2500ft, so I could see that taking some power out…but even corrected to sea level it was not hitting 13.5 @ 105 on my best run. The consistency was weird…here were all the trap speeds:
101.22
101.23
101.77
101.77
101.35
101.54
The 1/8th miles were all around 79.5 It’s almost as if no matter how I drove it, it always was within a 0.5mph of each other…all throughout the evening and the temps probably dropped 10-15 degrees by the end of the night. I even ran the car hot and cold. It’s almost as if the car was in a sort of limp mode and always limiting to the same power.
I am still somewhat new to the 4V world, so I need to learn what the problem areas could be. Here is the short list off the top of my head:
- IMRC’s (don’t know too much about these…can they cause big power loss?)
- Chip (I didn’t pull it out to see if there was a difference…but can’t see it causing a power loss. I spoke to Lidio and he said it advances timing and spark tables and little things like that)
- MAF – This is in the inner fender…haven’t even looked at, but what should I be looking for?
- Tune-Up – Like I said, it had this done, but I could double-check everything since God knows what they put in there.
- Motor – Hope not here…but a compression test would be my thought.
The only other thought I have is a fuel issue. I say this for two reasons:
1) It has a very bad problem of not starting….cranks forever and I think it is a fuel starvation problem. Gets much much worse when hot too.
2) I’ve noticed when I get under a ¼ tank of gas and give it WOT, it sometimes hesitate and seem to jerk or miss a little. Only happens when low on gas though.
I could start by replacing the filter (although this was supposedly done) and then check the fuel pump, but that's all I can think of.
Any thoughts or advice on where else I should start looking? I want to avoid throwing money at it and will probably only be taking it to the track one more time this year in September. If I don’t hit low 13’s with at least 105mph, it will be a very long winter.
Thanks
