Help with hesitation between 2000-3000rpm

[69mustangman]

I give. Short of going to the dealer I'm not sure what else to check for. What I perceive as the issue is a hesitation while driving in any gear between 2000-3000 rpm. Below and above is fine. In normal driving I go through that range quickly and don't notice anything. But if I happen to stay in that range then it feels like a miss or hesitation. Rpm shows no big changes (digital gauge). Needle is steady. At highway speeds above 70 I'm in the 2-3k range and it's annoying now.
Originally I noticed it with stock manifold, Airaid CAI and FR 84.5 mm tb, Lund and AED tuned. Changed back to stock tb, same issue. New plugs, same.
Now has the Kooks long tubes, off road H pipe, CJ manifold, twin 65, FR CAI, new coils, new tunes. Same.
Been on dyno while data logging and afr, short and long term trims are good. Gas mileage is normal, 25 hwy. runs fine other than the miss/hesitation between 2-3k rpm.
Could it be the wide open side pipes are exaggerating the effect? Is it normal and I'm just not used to it with the open pipes?
Thoughts?


Terry
Sent from my iPhone using Tapatalk

 

[VoodooBoss]

I've never experienced that hesitation. If you take it to your dealer they may not do much with the mods you have. Vacuum leak or an issue with the cam timing come to mind. Have you ever had the crank sensor relearn performed? It typically spits out codes if it's not right but it might be worth a try.

 

[athens7]

My car has always displayed what I call a slight "surging" between 2-3000 rpm. It feels to me like a subtle manifestation of inconsistency that equates to a hot cam or a very minor version of the jerking that the car can suffer when coming off throttle in first gear, then getting back on the throttle. I'm guessing it's either a problem with the electronic throttle linkage or the cam at low rpm. I have never mentioned it to my dealer; I accept it as a symptom of a performance car that would rather go fast than slow.

 

[69mustangman]

I've never experienced that hesitation. If you take it to your dealer they may not do much with the mods you have. Vacuum leak or an issue with the cam timing come to mind. Have you ever had the crank sensor relearn performed? It typically spits out codes if it's not right but it might be worth a try.

I did a crank relearn after I put her back to stock with the red key. No change.
I wasn't sure how they'd handle the mods. I had an intermittent vac leak after the CJ mani was installed and replaced the purge control valve. Per the logs after running up to 3000 and idling the trims appear normal. They were showing a 30% lean.
Thx


Terry
Sent from my iPhone using Tapatalk

 

[F.D. Sako]

I have the exact same symptoms.
Lately, I've been using the silver key, I think the hesitation is more pronounced with the silver key. I'll have to use the track key again and see if there's actually a difference, or it's just in my head. If there's an actual difference, then an aftermarket tune might fix it.

I'm also suspecting the driveshaft/diff for the cause of the hesitation, rather than the engine.

 

[69mustangman]

My car has always displayed what I call a slight "surging" between 2-3000 rpm. It feels to me like a subtle manifestation of inconsistency that equates to a hot cam or a very minor version of the jerking that the car can suffer when coming off throttle in first gear, then getting back on the throttle. I'm guessing it's either a problem with the electronic throttle linkage or the cam at low rpm. I have never mentioned it to my dealer; I accept it as a symptom of a performance car that would rather go fast than slow.

That's what I'm feeling. If I set the cruise and notice the surge then accelerate there's no hesitation while accelerating.
Had a friend at the dealership that has since moved to Florida tell me it's in the air fuel system. But I've switched back and forth with oem and FR tb and no change. Now with the CJ setup the only constant is the MAF sensor. Everything else has been changed.
Found a troubleshooting guide for the MAF that tells about voltage reading for the hot and 2 ground leads. If that has any merit then the voltage is off but then I should get a cel and she shouldn't run at all.


Terry
Sent from my iPhone using Tapatalk

 

[69mustangman]

Probably makes no difference but there's no hesitation or miss if I run up the rpms while parking. Slow, fast, in between it goes up smooth and returns with no evidence of a vac leak while many monitoring the shirt and long term trims.
Maybe it's just more noticeable with the kooks side pipes with a half inch restrictor plate in.


Terry
Sent from my iPhone using Tapatalk

 

[2012Boss302]

Per the logs after running up to 3000 and idling the trims appear normal. They were showing a 30% lean.
Thx

Am I reading this correctly?? The data log at 3000 rpm is showing -30%? Or is it reading +30%?

Either way, if it were a customers car in my shop, a -30% I would be looking for a rich running condition, ie: leaking injector, high fuel pressure, maybe the restrictor still installed in the CAI. A +30% I would be looking for a vacuum leak, malfunctioning/dirty MAF, or a clogged injector.

Keep us posted.....

 

[69mustangman]

While data logging I was asked to do a slow but steady pull to a specific rpm them idle immediately. At that time the engine was showing short term trim at 1.30 which I was told meant 30% lean and a vac leak most likely in the evap system. I plugged the inlet port in the mani for the evap control module and the lean condition went away. Sitting in the driveway there's no miss/hesitation at all. Under load is where it happens.
I've checked voltage and ground voltage on the MAF sensor and I'm only getting 3v on the wire that's supposed to be 12v (yellow with stripe) The primary ground is 12v but secondary is 0v. If I reading the right wires then that's saying the MAF sensor is bad. Just just don't want to chase another dead end. Put a 2015 sensor in and did the same thing but not sure if they are interchangeable.


Terry
Sent from my iPhone using Tapatalk

 

[SlowJim]

I have the same problem, although not a Boss. Have tried several tunes to no avail: BBR, Steeda, Hypermotive (AED), Lund, all have the same hesitation/surge you mention. I guess I've just learned to live with it

 

[69mustangman]

That's what others have said as well. I know what'll happen if I take it to the dealer, I'll spend the money and be told nothing's wrong. It'd be nice if they had a guarantee, problem fixed or diagnostic fee is waived.


Terry
Sent from my iPhone using Tapatalk

 

[F18SMM]

It'd be nice if they had a guarantee, problem fixed or diagnostic fee is waived.

I have only had that happen once and it was from a small shop. I was shocked at first but then realized it is a good way of getting repeat and new customers.

 

[Brandon302]

I have had this with my old motor and now with the new one. When I first got the car I had spoken to Steve from BFR and another guy at Summit and if I remember correctly they said they had a similar feeling. We surmised that it may be at a point where the cam position is changing and having it in that range causes it to switch back and forth.

 

[69mustangman]

Guess I'll shift above 3k and enjoy the sound and get used to the hesitation in 6th on the interstate.


Terry
Sent from my iPhone using Tapatalk

 

[Brandon302]

Guess I'll shift above 3k and enjoy the sound and get used to the hesitation in 6th on the interstate.


Terry
Sent from my iPhone using Tapatalk

That I would say is the only real issue for me, finding the right cruising speed that doesn't cause the hesitation can be very annoying.

 

[ArizonaBOSS]

How many miles on the car?

Might be a long shot--but try changing your fuel filter. $20 and it's good preventive maintenance even if that doesn't fix it.

 

[69mustangman]

Never thought of that but won't hurt. Started at 40k, now 52k


Terry
Sent from my iPhone using Tapatalk

 

[2012Boss302]

Might be a long shot--but try changing your fuel filter.

I thought the fuel filter was in the tank??

 

[69mustangman]

Hope not. Not going there


Terry
Sent from my iPhone using Tapatalk

 

[69mustangman]

Appears there isn't a replaceable filter. Can't find one and many posts talk about it being lifetime filter only replaced with pump.


Terry
Sent from my iPhone using Tapatalk