Cloaked Dagger

So I have the famous 3k rmp hesitation in my '93 R1. I just did the throttle position sensor adjustment(which it needed) and that sorted out my bucking and backfiring but I still have the hesitation. So I'm wondering what could be causing the hesitation other than the TPS. My mods are full 3" exhaust(no cats), pettit street port, pettit ported turbos, air injection deleted, PVC deleted, AWS was capped off when I bought the car, it's not a california model so it never had EGR, it had a pettit reflashed factory ECM when I bought the car before the port of the engine and turbos and the air injection deletion, 20B fuel pump.

FDHoward93

iTrader: (3)

The sure fire way to get rid of it is get a PFC or similar. Lol. The true origins of the 3K hesitation are still a little hazy. It is believed to be related to a grounding issue inherent in the stock computer. So whether or not it is reflashed you would still see a hesitation. Some people have had good luck just adding some additional grounds; like the free kit you can get from Pettit Racing. But I did that ground kit and I still get a significant hesitation until the car is fully warm. With your mods it will take the car longer to get fully warm which would lengthen the time the hesitation persists. But with all the mods you have put in, I'd say it is time to upgrade that ecu and get a good tune. It will likely yield a lot more hp.

Sgtblue

iTrader: (16)

^Agree. And nice answer Howard.
Every car seems a bit different when it comes to responding to the auxillary grounds. And warm-up is a must. You should never boost until at full operating temp anyway. IMHO the problem is technology, or the comparible lack of it 20+ years ago when it came to the ECU. Your's is re-flashed, but it's still the stock ECU.
The only other thing is that you mentioned "air injection delete"...I'm assuming that's the emissions airpump. SOME cars don't like that on the stock ECU. Effects seem to vary from 'no issues at all' to hesitation on throttle tip-in and goofy idle...especially when cold. I'm not sure if Pettit addressed it or not.

Apex Squeal

+1 another one here with the 3k hesitation. I just had an upgraded radiator, SMIC intercooler, and dual oil coolers put in, and I'm noticing the hesitation a lot more now. Maybe it *is* time for the PFC.

Cloaked Dagger

Believe me a PFC and a tune is definitely on the shopping list but I want to make sure I address all the other issues first. A new computer is no good if the computer is getting bad information from one of the sensors. A PFC would aid in diagnostics though since I could read the data stream with the commander. The other issue though is I just don't have the fat stack to drop on one at the moment, as soon as I do I will.

Swappedfd

u just bought a 93 fd and im having the same problem but im in the process of buying pfc and hope the problem goes away hope u find a fix

Hellstrom

Do you have the free Pettit kit installed?

93db

Have a '93 rx-7, with 3k hesitation. What are the chances the pettit grounding kit will help?

Jaemc

iTrader: (1)

I've got the same concern except it happens for me around 2k rpm upon coasting at city speeds. Car is bone stock aside from high flow cat and exhaust.

Sgtblue

iTrader: (16)

It certainly won't hurt. If nothing else it makes you're whole electrical system a little more efficient. I'm not familiar with the "Pettit grounding kit", but adding grounds can be as simple and getting a few feet of heavy wire (~ 8 gauge ?) from the local stereo shop or Walmart, a few decent crimp connectors and your time. All your doing is making a circle....engine to battery, battery to chassis, chassis to engine.
I'd also check all the OEM grounds too. There is one from the UIM to firewall and one on the left side of the engine near the plugs. Should also be a ground strap on the exhaust running from the aft cat flange to the chassis.