Well, I took off the UIM and freshened up the vacuum hoses, repaired several wires, and tested the injectors and the three air valves. That seemed to help a lot, especially when pressing the gas pedal to the floor. It had really bad breakup in the top rpms ... but it still tried which is more than what it did before. It still won't idle on its on tho.

Thought maybe it was the 4 year old gas that was in it. so i drained that and put in fresh 93 octane. ***This is the only thing i changed!*** Started it up and it only ran on one rotor for a few moments then died and quit starting all together. now it just turns over and usually floods itself. Unflooded and checked fuel pressure, spark, fuel lines, pump, maf. All are good.

I'm lost! Help!

 

I am running an FD fuel pump ... could it be getting too much pressure?

 

that sounds like injector problems.

well i havent started working on mine yet but i have been driving it alot lately and last night i got on it pretty hard and i got no or very little hesitation.

ill go drive her in a lil while and see if theres any difference.

 

i have the EXACT same problem i thought it was just the grounding that was bad because i read the forums and heard about a hesitation when the grounds are bad..but no luck..i thought it was a clogged cat..so i replaced it.then i replaced the whole exhaust from the cat all the way to the muffler..and still no luck.
so then i thought meaby it would be the spark plugs are bad but STILL no luck..

the problem was that the car would run fine if i just babied it but if i try to accelerate too fast it stutters and the harder i press it, the worse it is.and if i keep on the gas while it stutters when i let off it give me a huge backfire..so i really dont know what the problem is..i just want to be able to feel the cars full power just once..without having to stutter on the way up the rpm's..

 

ya we all know exactly how you feel.

right now mine is coming and going. sometimes i can boost really well and accelerate hard and then if i try it again. hesitation.

im gonna start with the fuel system and work my way from there.

keep posting what you have been trying and if you find a solution.

 

well tomorrow im going to take it to the stealership
so they can run codes
and run mechanical diagnostics on it..
gonna cost me about $105 hopefully they can spot the problem
after doing some extended research im 80% sure it might be a bad o-ring for the metering oil pump..it seems to be the most common thing to go wrong for this generation car and with leaks it can be pretty bad...so im hoping that it wont be the o-ring because i heard they can be pretty costly..
hopefully its something more simple than that like a gasket has gone bad in the Intake manifold and its simply doesnt get the compression it needs to climb the rpm's..i really would rather spend the money necessary to bring my baby back to the top than to have her running bad and STILL wonder whats wrong so its gonna be a win/lose situation..either way..

WISH ME LUCK
i'll report asap to help u guys out

 

check your water temp sensor it causes all kinds of fucked up things to happen also adjust you tps as per the fsm.

 

have you checked your pressure sensor it might be bad they rarely do but it happens and gives you those symptoms.
just backprobe the brown/red wire and it should be between 2-3 volts iirc.
also check if you have the right pressure sensor it should be n318 i had a hesitation for years and i spent thousands replacing parts until i found out my pressure sensor was for a n/a.
do you have the little pill in the vacuum line going to the pressure sensor?

 

I just started having this problem this morning as I was driving to work... Worked fine last night, great accelleration, wake up, and now it's cutting off at 4k rpms under hard throttle. Yet nothing when I baby it up through the rpms...

 

so has anyone gotten anywhere with theirs yet?

 

I had somewhat of the same hesitation problem. I changed my trailing coil and it fixed it some but not all of it. After changing plugs, wires and coils, I decided to wide band the car to see where A/F was. (I have a NEO) When I drove the car and the hesitation started, the Air Fuel ratio was in the 9s!

I went ahead and tuned low throttle with the NEO and solved the problem. Not sure if you have any kind of fuel controler but thats pretty much what happed to mine. I suggest to see if one of your coils is bad. Check the FSM, it tells you how to check them.

 

ok i thought i would update this.

my hesitation has stopped almost completely. and i didnt do anything lol.

i still feel it sometimes when it isnt completely warm but besides that its completely normal.

 

This is a problem I'm having too. and I don't have alot of money to sink into it right now to fix the hesitation. So someone please figure this thing out! I've replaced fuel pump/plugs/wires/coils and still nothing!

 

WOW this this problem is way to common, im having the same dang thing, from reading and having a bad maf in my mazda 323 where it would stumble with lots of peddle, i was able to readjust it but you cant with the S5 models the s4 you can tho.. and this problem was there before i installed my TPS so its no the tps, im starting to thinks its afm or map sensor as im driving if i keep my boost under -3 psi im ok but any thing bigger then that it wont take the fuel i give it, it just stumbles, but some times it will pull good for while il shut the car off feeling good that its fixed the next day same prob... im so confused as well

 

Sounds like poor fuel, could be your TPS, and if new plugs and wires seemed to help the hezitation, thats a sign that its ignition related.
You say its a fresh rebuild, it might only need breaking in. As you said its slowly starting to go away.
Im not too sure if the intercooler is helping any either. You didnt mention, but if you running factory boost, thats only going to help the hezitation, but I could very well be way off.
If your not running 93 octane, start filling your car with it.
I havn't read much of peoples post yet on this thread, but make sure your TPS is on good and has a good connection.
Might want to check out your MAF too. Make sure all your BAC lines are up to par.

Also, if you can't find the issue =/ just save your money and buy a standalone, you'll be able to make the car run however you want it to. Problem solved.

 

i agree, before any attempt on doing any type of upgrade you must make sure to replace all gaskets and make sure your car would be ready for it.

 

what RPM's were you feeling this hesitation? could of it been the secondaries?

 

I got a similar problem. Not only do I get a hesitation, But it studders from 4k-6k RPMs. I'm in the process of taking my UIM off and cleaning it out, and getting to the ground wire underneath it. I drive an 87 s4. Like everyone else said, The harder I'm on it, the harder it kicks me in the nuts. I've re-wired almost every ground related to it, except the one underneath the UIM. I also run premix, just replaced plugs and wires. all 4 leading plugs. It's a nasty hesitation. =[

 

well im having the same problem, in the way that when i start off normal and reach 3800-4000 i get this weird reaction like it wants to go but it doesnt, it starts bogging out.
im thinking its the secondaries cause it shows that it is boosting. im about to change the sparks right now and put in a small amout of Lucas fuel injector cleaner and fix the positive wire to the battery that its been damage.

 

Any more information on this?

I get the problem on my N/A when it's warm(ish). If it's stone cold, it acts moderately normal. Also the stuttering is around 2.5k rpm.

 

actually im gonna send you on to my other thread. maybe this will help maybe not.

im still in the process of trying to fix it but will update the other thread

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/flooding-while-driving-780880/

 

Ya, this is a completely separate problem. I noticed that the issue seems to go away when the heater is on full blast with the AC button pressed.

W.T.F.

 

Ive been having the same issue. It comes and goes....sometimes i can run thru the gears cleanly with no hesitation....other times it hesitates thru out the rpm range....Ive also noticed that it seems more likely to hesitate under part throttle rather than full throttle. I was going to look at the spark plugs and maybe the fuel filter.....its so weird that its not consistent

 

i ve been having this problem to my is a 87 n/a , i recently changed the pump,filters and plugs and also the tps. i also cleaned up the grounds under the uim it cleared sum hesitation in lower rpms but i still got hesitation between 4k rpm and 6k rpms