Hesitates at WOT and runs rich....

[93cobrajunkie]

I'll be home next week and I wanted to get some ideas for what might be wrong with my car. I have a 96 cobra with a KB 1.5, 03 cobra shortblock, MSD coil packs, CAI, mass air, and all the other supporting mods. Just replaced the evap solenoid and valve also. I bought the car from corral and found out it's been nothing but problems since. So my thoughts are it's more than likely a fuel or spark issue. So from what I've been told it hesitates when you punch it. After it hesitates it goes pretty good but seems to run rich. My brother knows a lot about mustangs so we've been trying a lot of the simple things and nothing seems to work. I replaced the coil packs with MSD because I figured with 14psi it's a good idea. That didn't cure it. The spark plug gap is .030 right now and he's going to widen it out to maybe .040 later. Just wanted to get some input and some ideas. It's not throwing up any codes right now, except the evap code. I'm waiting on a new clutch cable to come in so he can run it and see if that code goes away. let me know what you think, any questions just let me know. I'm going to check it out when I get home. thanks everybody.

 

[RIO RED SNAKE]

check the fuel pump too..what kind and lph isit using? It may be maxed out, also what size are your injectors? and was the car ever tuned? Also did you try the MAF...if it is stock it is tapped out get a lighting 90mm maf or bigger..

 

[93cobrajunkie]

check the fuel pump too..what kind and lph isit using? It may be maxed out, also what size are your injectors? and was the car ever tuned? Also did you try the MAF...if it is stock it is tapped out get a lighting 90mm maf or bigger..

The kid I bought it from doesn't seem to know crap. He said it had a "bigger" fuel pump and didn't need to run a boost a pump or anything. Not sure about the injectors. It was tuned out in California the way it is. There's a fuel pressure gauge mounted inside. If the fuel pump was bad why would it run rich? It has a 90mm maf. I'm gonna look at all the receipts that came with it when I get home. I was thinking about getting some of that seafoam stuff. I heard it works wonders. It's only 10 bucks too.

 

[harvboi05]

dont trust anything th previous owner said. take the injectors out and have em cleaned/flowed. you said you replaced the coilpacks and that the plug gap is .030, but not if you replaced the plugs. replace the plugs make sure the gap is .030 on all of em. if you make the gap wider chances are you still start to blow out, if you arent already.

how do you know its running rich? do you have a wideband? if not, get one. then youll know for sure where youre at.

whats your fuel pressure at with the reference line off?

seafoam will not do anything to fix your WOT. take ur 10 bucks and buy an extra set of plugs and gap em down to .028

take the car to a quality calibrator to make sure everything is ok before you blow it up.

 

[RIO RED SNAKE]

because if the car is cuttin gout then it is starving for fuel for that second or is missing...so do the new plugs, and 14lbs of boost is alot which could mean the fuel pump is upgraded but it is still not enough fuel to handle that much boost..same with the injectors..i have a 1.5 Kb and have 42lb injectors and a walbro 255lph fuel pump...idk see what happens but i think you deff need a RETUNE!

 

[PSUCOBRA96]

first find out what injectors you have, the stock 24's aren't gonna be enough, get a new tune and find out if the MAF is pegged and check the plugs. Plus if it is tuned in Cali it is likely meant to run on 91 so if you have 93 in MI you want to take advantage of it so you can add more timing.

I wouldn't open them up to .040 try .036 or .034. Also replace the plugs while you are there. Also the MSD coil packs are not gonna help you and are much less reliable, stock is your best bet.

Also when was the last time your wires were replaced? And does the car sit a lot, the car may have clogged injectors or crap in the pump if it sits for a long time. Put some fresh gas in it with some seafoam in the actual tank to help clean out the lines.

 

[93cobrajunkie]

dont trust anything th previous owner said. take the injectors out and have em cleaned/flowed. you said you replaced the coilpacks and that the plug gap is .030, but not if you replaced the plugs. replace the plugs make sure the gap is .030 on all of em. if you make the gap wider chances are you still start to blow out, if you arent already.

how do you know its running rich? do you have a wideband? if not, get one. then youll know for sure where youre at.

whats your fuel pressure at with the reference line off?

seafoam will not do anything to fix your WOT. take ur 10 bucks and buy an extra set of plugs and gap em down to .028

take the car to a quality calibrator to make sure everything is ok before you blow it up.

yeah I plan on taking it up to ford and having them do that test where they check all the sensors to make sure all that stuff is good and I was gonna have them check the A/F ratio. My brother said it's running rich and I usually trust him. It blows some black smoke when you get on it. Once I get to look at it myself I'll have a better idea. My brother is a pretty good mechanic and knows his stuff. I'm also a mechanic so once I get home I'll have a better idea what I'm dealing with and I'll be able to get the finer details. Do you have to drop the tanks on the SN95's to get to the pumps? I've just had new edge cobra's mostly.

 

[93cobrajunkie]

first find out what injectors you have, the stock 24's aren't gonna be enough, get a new tune and find out if the MAF is pegged and check the plugs. Plus if it is tuned in Cali it is likely meant to run on 91 so if you have 93 in MI you want to take advantage of it so you can add more timing.

I wouldn't open them up to .040 try .036 or .034. Also replace the plugs while you are there. Also the MSD coil packs are not gonna help you and are much less reliable, stock is your best bet.

Also when was the last time your wires were replaced? And does the car sit a lot, the car may have clogged injectors or crap in the pump if it sits for a long time. Put some fresh gas in it with some seafoam in the actual tank to help clean out the lines.

I was under the impression that MSD coil packs were better. Didn't think the stock ones were made for boost and the MSD ones were. I was told by the previous owner that they were replaced recently but I don't trust a damn thing he says. I'm gonna check the injectors when I get home. My mom has been driving it so it has fresh gas. I'll have some better details for you guys when I get home. Thanks for the ideas. I'm gonna check the injectors and pump first. Doesn't make any sense why they would bother dyno testing it with a crappy fuel system. It put out 418rwhp and 468rwtq. Didn't think the stock injectors could handle that.

 

[93cobrajunkie]

I was also going to data log it with the SCT tuner.

 

[RIO RED SNAKE]

well if i tput down that hp then deff after market pump and injectors..but to get to the fuel pump you DO have to drop the tank

 

[93cobrajunkie]

well if i tput down that hp then deff after market pump and injectors..but to get to the fuel pump you DO have to drop the tank

is there a test you can do to see if the pumps are bad? Usually with electronic parts you just do a resistance test and if it's out of that range the part is bad.

 

[RIO RED SNAKE]

ehh idk i am sure there is but i dont know of it...

 

[93cobrajunkie]

maybe I'll give ford a call next week, I'm sure they know how to bench test them.

 

[Toasty]

I'll be home next week and I wanted to get some ideas for what might be wrong with my car. I have a 96 cobra with a KB 1.5, 03 cobra shortblock, MSD coil packs, CAI, mass air, and all the other supporting mods. Just replaced the evap solenoid and valve also. I bought the car from corral and found out it's been nothing but problems since. So my thoughts are it's more than likely a fuel or spark issue. So from what I've been told it hesitates when you punch it. After it hesitates it goes pretty good but seems to run rich. My brother knows a lot about mustangs so we've been trying a lot of the simple things and nothing seems to work. I replaced the coil packs with MSD because I figured with 14psi it's a good idea. That didn't cure it. The spark plug gap is .030 right now and he's going to widen it out to maybe .040 later. Just wanted to get some input and some ideas. It's not throwing up any codes right now, except the evap code. I'm waiting on a new clutch cable to come in so he can run it and see if that code goes away. let me know what you think, any questions just let me know. I'm going to check it out when I get home. thanks everybody.

You should be running .032-0.34 plug gap. Factory coil packs are fine, and in fact the MSD's have been known to cause tune/driveability issues on our cars.

You need to get the car on a dyno and have a tuner take a look at the datalogs. Has the car ever been tuned since the 03 shortblock and KB were installed?

 

[Toasty]

yeah I plan on taking it up to ford and having them do that test where they check all the sensors to make sure all that stuff is good and I was gonna have them check the A/F ratio. My brother said it's running rich and I usually trust him. It blows some black smoke when you get on it. Once I get to look at it myself I'll have a better idea. My brother is a pretty good mechanic and knows his stuff. I'm also a mechanic so once I get home I'll have a better idea what I'm dealing with and I'll be able to get the finer details. Do you have to drop the tanks on the SN95's to get to the pumps? I've just had new edge cobra's mostly.

Taking it to a Ford dealer will, in all likelyhood, end up being a moneypit. Stealerships dont usually see modded cars, especially one with a blower. Find a SCT tuner in your area that has a dyno and work with him to resolve your issues.

 

[Toasty]

well if i tput down that hp then deff after market pump and injectors..but to get to the fuel pump you DO have to drop the tank

If it has a KB Boost-A-Pump installed, it can make those numbers with a stock fuel pump and injectors. Barely.

Does the OP have a boost-a-pump installed?

 

[RIO RED SNAKE]

im not sure toasty..he said the kid he bought it from didnt knwo jack about the car...therefore he doesnt know jack, someone mentioned boost a pump but he said it had a bigger pump...so who knows...i think he needs to go to a tuner and get ford coil packs

 

[venom1997]

those a pretty stout numbers for a 1.5l at 14 psi do you have a forged motor? i could not get that much tq from my set up im running meth, ported heads/ported imrc plates the whole works long/tubes etc... 9.5-10 psi


OH i would get rid of those coil packs and get some oem ones a lot of problems come with aftermarket coil packs there are guys running 800+ rwhp with stock packs

 

[Toasty]

im not sure toasty..he said the kid he bought it from didnt knwo jack about the car...therefore he doesnt know jack, someone mentioned boost a pump but he said it had a bigger pump...so who knows...i think he needs to go to a tuner and get ford coil packs

+1

 

[Toasty]

OH i would get rid of those coil packs and get some oem ones a lot of problems come with aftermarket coil packs there are guys running 800+ rwhp with stock packs

^^^^^^^^^^^^^^^^^^^^^^

What he said.