rx7_turbo2

I don't have the reason why, maybe it was just a coincidence, but....

After some mods my car became ill with the 3800RPM hesitation problem. I grounded the boost sensor and ECU and all the usual stuff but it fixed nothing. I was able to minimize it with tuning of my S-AFC but there was always a hint of it still there. I changed my O2 sensor today and bingo hesitation is gone completely.

Those of you techinical wizards might be able to explain why, but all I care is that it's gone.

10TH_ANNIV_T2

Interesting. Where did you get the O2 sensor, and who makes it, etc?

Thanks,

Greg O.

Sniper_X

Costs $18.

rxspd

I heard if you ground the **** out of everything, like more than just 1 wire it will stop it, does anyone else who has done that care to comment?

Sniper_X

I don't beleive in the grounding thing.

I mean , I KNOW that the ground CAN be a problem. but it requires almost NOTHING to ground the car properly.

Most people that I have seen that grounded the heck out of the car to stop the hesitation have been shocked to see me cut all but the factory straps and the hesitation is still gone.

Its injectors, a bad vaccum valve, vaccum conneciton, sensor or other electromechanical part.

7 out of 10 times.

I've proven it on the last 5 cars I've serviced for this problem.

Clean the factory grounds, and leave it at that.
Make sure the factory ground locations are secure and seated, and move on to the real problem if it persists...

RETed

You're talking about hesitation under light throttle or WOT?
If it's WOT, it really has nothing to do with the O2 sensor.


-Ted

Vroomaster

I ran an extra ground from the bottom block to the firwall and my idle is rock steady, where it wasn't before.

Sniper_X

How are your FACTORY grounds?

Healthy?

If an extra gound fixed it, then put a meter on the frame when the factory ground starts and then on the engine where the factory ground ends.

check all the grounds this way.

Make sure that you loosen, and clean each.

The remove your extra ground.

Voila.

And I know about the WOT thing... but I find it faster to make sure all the factory stuff is fine first, then debug then, most of the time the problem goes away without having to RIG somthing or chase a spurious ground.

88 vert

well help me with mine i have new exhaust (from header to mufflers),injectors,O2sensor,and new K&N cone air filter also have cleaned and grinded all paint off where the ground mounts,added extra grouns 1 at a time starting with the ECU then to the battery cable then to the original grounds then to the boost sensor each time i have done this i reset the ECU and went for a drive the only difference i noticed was when i grounded the boost sensor(felt like it went from 1 hesitation to several hesitations) i only done 1 ground at a time and even recently swapped the ECU and still with no luck i beat my head against the glass everytime it hits 3800.this is on a 88vert that had the stall before and after mods i agree i thought it had to be something bad to cause it so i tried testing and replacing each part 1by1 from the ECU to the AFM then started to ground and still no luck

Sniper_X

Is what I always do when I dont know the pathology of a malfunction...

I use procedure...

Step by step, check ou all components that at 3400 -4000 RPM:

Turn on
Turn off
Or otherwise change operational state

The grounds are clearly not your problem.

I will look into the sensors and switches that operate in the RPM rance that i mentioned above, but you should be able to check them with the Factory Service Manual.

Let Me know what you find.

LoSRx7

Can someone show us the locations of the grounded spots. Anyone have pics of the areas, or a write up on the location of the grounds?

blu_gxl

well i tried to add extra grounds worked untill i started throwing on mods then it came back but, it seems to have gone away due to the use of mmo. i think mine was related to a cloged injector due to this.

james

XLR8

iTrader: (52)

I have an 88se that hesitated so bad it would barely rev past 4k. I regrounded the grounds on the ECU under the passengers floor and it fixed it. It's still very faint at times, but it is a world of differece.

88 vert

i will definately keep trying to get rid of this problem and i will post what i find i only do one thing at a time and then road test it so that way when i find it i can post and maybe help some other people with this stubborn hesitation if anyone else as any ideas on where to go next please HELP Thanks,Dave

downwinddave

My "new" 91 vert DIES at 4000 every once in a while.
Never had the problem on my 89. Will proceed to check engine fault codes and grounds, Mahalo.

TRURX7

In my car,
ran grounds = helped
used a 1 farad cap = problem dissapeared and has not come back in 2 months so far.

RX7BEAR

I have an 87 GXL and Im going nuts with this crap !!! It bucks at 3800 and is very embarassing . What grounds are you all talkin about got any pics of them? I put brand new injectors in and intake gaskets and new silicon lines. complete tune up. What else?

HAILERS

RX BEAR....When you did the new silicon lines, did you reinstall the orifice in the boost/pressure sensor line?And for the folk who did new injectors, did you upgrade to larger injectors???? Perhaps your flat too rich and that is causing the hesitation.

silikenrf

The TPS in the 2nd gen's fails slowly starting with a series of hesitations which manifest themselves into a car that feels like its ready for a new motor (cracked Apex).

Ask the Guru's - I'll bet they've seen this 100's of times.

Angel Guard Racing Team

The guy fixed it by installing an O2 sensor. Of course it is not a WOT hesitation. He is all happy driving around with his problem fixed and you guys are still here trying to tell him what to do.

nima_taba

Where do we put the 1 Farad capacitor in??
Will this actually work? I'm willing to try anything

Icemark

It will only work if your battery or alt are not up to factory specs.

I would also be leary of TRURX7's comments on this cap thing, as he sold the car a month or two back and was never able to really test to see if this solved the problem.

skotter

Guys,

I just replaced my old exhaust which had multiple leaks with a new one. The 3800 hesitation is now gone. This would lead me to believe that it is caused by insufficient back pressure. Can anyone else confirm?

HAILERS

I can't buy into this theory. My car works fine with the stock exaust system and works good with the full Racing beat dual system from front to rear. Then again, your hesitation is gone. I guess the proof is in the pudding. Oh well.

Icemark

More than likely you fixed the back pressure enough to activate the 5th/6th ports