i finally found out what was the problem with my car's hesistation. i got desperate and tried an aftermarket fpr, adjusted the pressure and that's it!! no more hesitation. i drove it for 2 days to make sure before i posed. i noticed when i turned up the fuel pressure the needle on the fpr gauge would bounce, kinda like the hesitation did. i think this will atleast help a few of us. as for the 3500 hesitation, 90% of the time i dont even feel it. the other 10% it is so barely noticeable. i dont know what this has to do when it is warmed up or not but my car did the hesitation only when hot. how would the fpr act up only when warm??

anyway, im so happy with my car, no more hesitation!!!!!!

 

so what fpr did you go with? i have been pondering the fuel pressure myself pump i was thinking more along the lines of the pump

 

i went with an adjustable rising rate. a bud owed me money so he gave me this.

 

very interesting.. I wonder if we could troubleshoot for that by unplugging the line to the FPR (for us w/o adjustable FPRs). I wonder if when we get the hesitation, the FPR vacuum line pressure is oscillating or something

 

i think it has to do with the return. when i was playing with the fuel pressure. i noticed when i tried to turn up the fuel pressure to 30+psi on idle anything past 25psi and the needle started bouncing. i think the stock fpr was too small to return with the warlbro and was running too much pressure at idle & under vacuum which would cause the "bouncy" hesitation. but when the boost climbed, the extra fuel was then being used, that is why the hesitation stopped under boost. that is my best idea i could come up with.

i dont know how it could only do this when hot, but mine hesitated when hot and ran fine when cold. but doing this fixed this problem completely for me.

 

Sounds like bandaid more than a fix

 

how the heck does this sound like a bandaid??? the regulator wasnt regulating the pressure because of the bigger fuel pump so i replaced it. a band aid would be putting in a regulator off a different vehicle or something. tell me what would be the proper way to fix what i did?? i replaced the regulator...and it runs like new....hmm.

 

because you your self don't fully know why it corrected it. A lot of fc owners use the walbros without an aftermarket FPR...thus I said is SOUNDS like a bandaid...I never said it was a bandaid.

 

i dont think the fuel pressure should heavily pulse. every one ive seen stays still. as soon as i got the pressure to steady, the car ran perfect. when i put it back to stock, it pulsed and ran like ****. nothing else was done. nothing else controls the pressure. i think something in the stock regulator goes bad, making fuel harder to go back to the fuel tank. because of the extra pressure, it has to "work" harder?? anybody have any other possible reasons???

 

Our cruising hesitation problems seem to have this in common:
1) occurs between 2k - 3k rpm
2) occurs in vacuum, up to 0 psi
3) rtek 2.0

the fuel pressure regulator only sees 1) vacuum and 2) incoming fuel pressure. If it was a bad fuel pressure regulator, wouldnt you have the problem at all rpms in vacuum? but we only see it between 2k and 3k rpm. I mean if i keep it under 2krpm, it will drive perfect, no problems at all

i could be wrong, but it seems it is more related to closed loop mode. i think it is more than coincidence that it stays in closed loop when you are
1) 2k - 3k rpm
2) in vacuum, up to 0 psi
pretty much the same conditions we are seeing the hesitation. Makes me think there is a bug in the software, where the injector presets and/or the user fuel correction is messing with the closed loop code, causing it to go way lean where it shouldnt. almost as if the fuel correction is throwing the closed loop calculations off, because the feedback is way different than what it would normally be getting with stock injectors

 

have you tried to unhook the o2... not the wideband gauge but the 0stock o2 wire what have you done with that? i have mine not hooked to anything and its runs fine now after wb02 install

 

my hesitation gets worse with stock o2 unplugged. are you using the wideband o2 0-1v output instead? or just nothing connected?


mzrx7man, do you have wideband?

 

I know when I had the hesitation problems before I had the Rtek 1.5 or 2.0 I put in new grounds it helped with alot of it. When I had the 1.5 I put in the Aeromotive fpr the car felt a whole lot smooter and it actually got easier to tune. I remember reading around on this forum and teamfc3s that the Walbro will overrun the stock FPR and cause some hesitation problems. I have no problems with the 2.0 currently. I might get some hesitation, but its from my own throttle inputs and maybe not having a few things on my throttle body.

 

try running a new wire for the O2. have you checked for resistance oin the O2 wire?

 

yes i do.

 

what happens when you disconnect the line to the FPR? does it default to ~40psi? I wonder what would happen if you just run it like that, 40psi all the time and tune fuel map in vacuum to compensate for increased pressure.. or is the constant fuel pressure increase bad for your injectors/line/&fuelpump?

im going to try this and see if i still get the hesitations.

also will try swapping in a different tps later today:

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/low-throttle-cruising-hesitation-540270/
this guy had very similar problems, and a new tps fixed it

 

well i tried a new tps and also tried unplugging the FPR and both times i still got the hesitation. When i had the FPR unplugged, the AFRs were almost a point richer, so i know the fuel pressure had to have gone up.

with the fpr unplugged, the fuel pressure should not be fluctuating, right? or maybe that is the problem, that it could be randomly fluctuating

 

that is what i have been trying to say at first. maybe i didnt explain it right, but that is what i meant.

 

If the FPR was truly the case, People other than just Rtek users would experience the same problem.

 

i think this very may well be my problem.

tonight i was driving around and for some reason my nb o2 gauge was constantly pegged lean, and the rtek showed it at 0v. i think my o2 sensor may be fouled or something.

anyway, with it stuck a 0v, I was also able to easily control the hesitations with the throttle.. the wb would lean out to 17-18 whenever i keep constant cruising throttle, and would go rich (12-13) if getting into boost or letting off throttle. you could easily tell that whenever the ecu went into closed loop mode, the wb would lean out and get the too familiar hesitations..

I think my problem is the o2 sensor line is picking up interferrence or something, maybe my nb o2 gauge is loading the signal. tomorrow im going to try check the wire resistance and disconnect the nb o2 gauge. possibly run a new shielded wire

 

^^^^ Make sure BOTH side of the shielding is grounded. That is the wire wrapped around the O2 signal wire. I would run a new one and see what happens. When you check resitence, unplug both sides of the O2 wire. At the O2 and at the ecu.

 

i checked resistance in the stock o2 wire, came out to be about 12 ohms. I ran a new shielded wire through one of the firewall AC grommets and checked the resistance, right on 0 ohms.. grounded the shield on both sides. I also cut out the nb o2 gauge and installed a new o2 sensor. took it for a drive and the problem appears to be gone! but im not getting my hopes up, hopefully it wont come back

 

what happens if the shielding is not grounded? just ground it to the exhaust on the sensor side?

 

actually im still getting the hesitaitons, but very rarely, seems the new o2 wire made a big difference though

 

As I understand, both ends are to be grounded or it does not complete the loop.