Looking for some advice. Car is a 97 cobra with a stock motor other than imrc deletes. Under acceleration, car hesitates and bucks. Fuel injectors are 2 years old, and using the screwdriver and stethoscope method i heard them all click. Fuel filter was replaced at the same time 2 years ago. Plugs and plug wires are brand new. No vacuum hose leaks. Premium gas. Compression test had 180psi give or take 2 in each cylinder. Problem gets worse if i put it in say third when i should be in 2nd and try wot. Stumped. Any ideas what it may be?
97 cobra hesitation on acceleration
- Thread starter v8musclecobra
- Start date
Also i should mention idle is completely fine.
if its not a slipping clutch Id vote coils or wires.
in neutral it wont be under load but if you give it a strong rev does it pull cleanly?
in neutral it wont be under load but if you give it a strong rev does it pull cleanly?
Do you mean if i rev it in neutral at a stand still does it show any hesitation? No it does not.
What plugs and plug wires.
That is most likely your issue.
Also: Did you get a tune after the IMRC delete? At what RPM is the stumble?
That is most likely your issue.
Also: Did you get a tune after the IMRC delete? At what RPM is the stumble?
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Plug wires are ford racing. Plugs are ngk nitrous plugs. Ive used this brand And model for maybe 6 years on the same motor and never had a problem before. Yes, tune was done when i did the imrc’s maybe 9 years ago. Also reflashed the system today with the same tune but the car is unchanged. Stumbles kind of through the rpm range now, but started off just at low rpm ( under 2000).
Newer Ford Racing wires are no good anymore (not like they used to be anyway), and these engines run best on Autolite 764s gapped at .054
Coils.
Get motorcraft only....
That is all....
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Get motorcraft only....
That is all....
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Had same issue. Ford racing are junk now. Don't do msd either. For some reason these engines love this combo...
Ford motorcraft coils , Ford motorcraft grey wires , and autolite coppers.... As stated above.
And if you can't find the OE grey wires , Denso made the motorcraft wires for that year
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Could also be a vacuum leak as well. You getting any lean codes?
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Didn’t know that about the plug wires. I just replaced the coil packs with an aftermarket set i had and it didn’t change anything, but they’re not motorcraft. I had one vacuum hose that had a small crack that i replaced today but it’s still the same. No codes unfortunately. Will try getting motorcraft coil packs and see if that solves the problem. Will also look into those plug wires. Sucks because i just bought these things. Thank you all for your help so far. Keep the recommendations coming!
Check for pending codes too
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Oem coil lacks can be had on eBay cheap.
I would have mentioned those too, but the op never mentioned that he swapped them out.
OEM only for the 96-98s, as far as spark goes.
I would have mentioned those too, but the op never mentioned that he swapped them out.
OEM only for the 96-98s, as far as spark goes.
Yep oem provides PLENTY of reliable spark. And I've found that the oe wires seat better on them. If you can't find motorcraft at a reasonable price , denso makes the motorcraft coil , also denso made motorcraft wires if you can't locate them too. Part numbers posted below.
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Also a good idea to check the ignition coil connectors
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Oem coil packs are what i had ( circa 1997 ). The aftermarket ones i just put on did help slightly so i’m thinking i try buying new oem packs and the plugs mentioned and see what happens. Thanks so much for the part numbers!
Finally got the denso ignition wires. Called ford for the oem ones ( like to keep stuff like that as stock as i can, only bought ford racing a few years ago cause i couldnt find any blue oem wires) and ford wanted $175 for a new set. Put them on and it made it better, but not perfect. Then realized i put on a pair of cheap aftermarket coils on after it was mentioned it may be coils. Put the oem coils back on and problem is totally gone. I’ll be honest, i was skeptical that was why it was running so bad. Ford racing plug wires are only 2 years old! Thanks for the help! Car runs like new again.
glad it's resolved, thanks for updating with the solution
Excellent.
These 96-98s have a picky spark.
These 96-98s have a picky spark.
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