Ive been having a small window of hesitation with my engine for a little while now.....Here's what ive done to try to fix the problem so far: replaced fuel filter, all 4 spark plugs, cleaned grounds, had injectors professionally cleaned, and a different TPS. A friend of mine had a spare TPS that we put on my car. he had no idea what kind of shape it was in, but after we put it on, the hesitation was still there. the engine hesitates from 3k to about 3500rpm...sometimes it starts a little bit before 3k.....I have another TPS on the way, that i will also adjust.....right now im suspecting a dead spot with the TPS....i just wonder, what are the odds of 2 TPS's giving me the same problem (altho is quite common for the TPS to develop these dead spots from what I've read so far)...Does anyone else have any other ideas?

 

um the usual 3500/3800rpm famous hesitation where the "transition period" primaries are cutting off and the secondaries are coming full on. its a "dead spot" on almost every FC. solution is get your ECU reflashed from digital tunig. extremly easy and affordable and gets rid of alot of problems for the N/A rx7 and the T2 mainly for the s4 rx7 some for the s5. check out the website alot of info there.

 

its not a specific spot that i see a dip in power, but a small window...this transition shouldnt be giving me hesitation as early as 3k should it? Sometimes the car gets shakey thru the hesitation period (depending on how much the throttle is open and how much of a load the engine is under)....its more noticeable going up hills under part throttle in any gear

 

I just did an advanced search for "injector transition" and i found an interesting thread...the members in that thread are having the exact same issue as me...the thread is like 2 yrs old and there didn't seem to be a solution to the problem...altho, the TPS was brought up as a possible cause of the problem.....

 

if you have a 6port it could be your actuators are failing to open under load, there are two of them and if one is sticking then you will get a small hesitation when the 5th and 6th ports open up to increase power, if you cannot move the rods by hand then you have a problem, one of mine is fine and the other hesitates a bit you can clean them if that is the problem however they are pretty cheap second hand and fairly easy to replace, front one is a bit more difficult, removing the air pump makes it alot easier

by the way if you do have an s4 n/a 6 port the actuators are activated ONLY by exhaust backpressure there is no electrical connection or anything also alot will argue that this doesn't work but I know for fact it does - to test them you can have the engine running and shine a light at them ( so you can see better ), reach over and rev the engine it will take more RPM's b/c you have no load but they WILL open ( you will see the rod pump up and down as you rev up and down ) still if they don't you have a prob with them

 

Thanx for the ideas....My actuators and airpump were removed before i got the car.......since there arent any actuators controlling the movement of the sleeves, its possible that they can be moving a bit just from the movement of the car/engine as i drive. The car ran perfectly when i got it tho....toward the end of the summer is when i started to get hesitations.....I was reading thru some posts on the 3rd gen forums....it seems that the 3k hesitation is common for some of those cars.....some thing its caused by the transition of the injectors....both stock ecu powered cars as well as standalone/piggyback powered cars have this issue....noone has really come up with a sure shot solution....standalones and piggybacks allow u to alter fuel settings that will mask the problem but it still exists in some cars.....some have replaced the ecu and the hesitation goes away, others do the same thing and the hesitation stays...same with the tps

 

I remember reading somewhere that a ground can be redone to the ECU to help out..

I would recommend getting some new actuators and putting them on there, with the ports wired open you may get a little less power in the low end, there are a bunch of people that swear by wiring them open as a quick fix to the hesitation, its really just easier to replace them, I just picked up a set for like 12 bucks from a guy on here, now if the PO didn't wire them open and just removed them I can see that being the root of your evil b/c the MAP is expecting more air to come in but it never happens... I dunno I am no tuner or expert by any means that is just where I would start looking

 

I have an aftermarket exhaust with no cats.....I'm not looking to replace the actuators b/c the lack of back pressure in my exhaust won't allow them to work properly anyway. The car ran like a champ when for the longest time after i got it, so i don't think non-functional aux port system is the problem