Crazy all the folks saying TR6's cause hesitation, great! I have a brand new set in my fresh motor waiting for the first start, looks like I should dig the 764's out of the garbage and trade places with the TR6's 
Cobra hesitating at 1500-2100 rpm?
- Thread starter stang8762
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Crazy all the folks saying TR6's cause hesitation, great! I have a brand new set in my fresh motor waiting for the first start, looks like I should dig the 764's out of the garbage and trade places with the TR6's
If you're blown then you'll want the 103's. They're the same heat range as the TR6's. I'm running TR6's without any issue. My stumbling and bucking was EGR related. Once I turned it off the car ran smooth.
Is this only when its cold? Something I noticed with mine is when its cold, if I get on it where the S/C boosts, I totally lose power/acceleration... feels like you hit a rev limiter or something. Light easy acceleration is fine when cold, it only happens when I get on it hard.
Once the car is at operating temperature, I never feel it again. :shrug:
You shouldn't get into boost when the motor is cold. Wait until it's warmed up to play. Is the car tuned? It sounds like a problem with the cold start table.
Good to know. My first S/C vehicle. At this point I don't get on the throttle anymore until she's at running temp.
Unsure about tune; I'm 4th owner and previous owner did not. It's only running a MAC straight shot cai and H/R springs so unless it was modded by 1st two owners, I doubt its been tuned.
It might be the sensors. It seems a lot of people have issues with aftermarket sensors. I've only run the Motorcraft personally.
Does it still have the stock pulley? If so, take a pic. I can't remember the last time I saw a stock pulley on a Cobra.:banana:
Stock pulley AND pulley guard.... FTMFW! ;-)
Having a similar problem. My cobra has a stumble between hard or WOT shifts once the throttle is left off for gear change and then applied again at half to full throttle? My cobra does this after I had it professionally tuned for eaton swap. Some have said it is the PPRV dumping off to much fuel on decel and does not have enough fuel momentarily when going back on the throttle hard...
My stumble isn't that hard. Normal people probably don't notice it. With that Lucas Oil octane boost, it is almost all gone. I re-gapped and clean my plugs and I didn't notice it today. I lit the tires up pretty easily today too. Got on it from a roll in first, spun, hit second and got sideways. Later a buddy in a Talon was revving to make noise with his blow out valve and I just blipped the throttle when I let in the clutch and did a quick burnout. Next fill up I won't use the octane boost and see what happens.
I know that this is a really old thread with little hope, but I'm having the exact same issue. Slight hesitation from like 1800-2100 rpm. Was this issue ever resolved? I'm thinking it may be in my tune, since it does not hesitate in that region when cold. At op temp, all the time. It is painful to hold it at 2000rpm because it will sputter like crazy. Runs awesome everywhere else though.
I had two bad coils, check the resistance across your coils.
Is there a specific range they should be in? I have a set of coils in the garage and I know one or two are bad. I'd rather not have to play the swap the COP game.
So I replaced all the coils with FR 4V kit, brand new NGK TR6 plugs, and while I was at it upgraded to 80#ers. Hesitation is still there.
I have a really aggressive cam in the car. But I don't have the Hesitation when the car is still in warm up, just at full temp.
I have a really aggressive cam in the car. But I don't have the Hesitation when the car is still in warm up, just at full temp.
Did you get a tune for the 80's? If not you just introduced another problem.
Yes, I have Sct pro racer. Tuned for 80s and MAF transfer function calibrated.
I feel like I should give as much information as possible to help diagnose.
I have the SCT PRP. Here are the important mods; Crower stage 3 cams, oversized valves, ported heads, ported/polished upper plenum, stock throttle body, GT pumps, 80#s.
Car is set up blow thru, Novi 1000 with A/A intercooler. BA5000 MAF in a 3" tube. Straight shot, no bends probably 9" before the MAF and 4" after. I BOV right after the blower before the intercooler so there is a ton of space between the BOV and the MAF.
It almost feels like that MAF is getting backwashed, but the datalog doesn't seem to show it. My wideband does seem to go lean in that area, but MAF transfer is good there, because there is no issue passing through that RPM band at WOT. This is strictly a part throttle issue.
Please tell me if there's anymore information I can give to help narrow down. Thanks.
I have the SCT PRP. Here are the important mods; Crower stage 3 cams, oversized valves, ported heads, ported/polished upper plenum, stock throttle body, GT pumps, 80#s.
Car is set up blow thru, Novi 1000 with A/A intercooler. BA5000 MAF in a 3" tube. Straight shot, no bends probably 9" before the MAF and 4" after. I BOV right after the blower before the intercooler so there is a ton of space between the BOV and the MAF.
It almost feels like that MAF is getting backwashed, but the datalog doesn't seem to show it. My wideband does seem to go lean in that area, but MAF transfer is good there, because there is no issue passing through that RPM band at WOT. This is strictly a part throttle issue.
Please tell me if there's anymore information I can give to help narrow down. Thanks.
I'm trying to remember if I had that issue. I ran 80's with a BA5000 in a 3.5" tube. It is possible you have some turbulence in that range. I believe CX Racing makes an air straightener. It might be worth looking into for your set up.
Is the graph for the MAF transfer smooth? No bumps in the range you're looking at?
Is the graph for the MAF transfer smooth? No bumps in the range you're looking at?
I'll datalog the car again today and try to get the worst hesitation. Thanks for taking the time to help.
I recently resolved a low rpm hesitation that I had been dealing with for a few years.
Couple of questions.
Do you have the EGR system up?
How old is your serpentine belt? Condition?
Is your AC compressor still on the vehicle?
Yes, EGR system is stock.
Serpentine has about 1500 miles on it, good shape, no fraying
AC compressor is still on vehicle and works normally.
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