After it warms up it runs fine.

But crossing from 3800-4000 rpm (when the computer switches to its internal fuel maps, it misses a bit,

I thought I had it licked, but nope.

Its only until it warms up!

It would be great if someone had fixed this before and could cut to the chase on thism ive beel all through this motor!

 

Um... why are you running above 3200 RPMs when engine is cold?

 

Have you made sure your secondaries are firing properly?

 

Yeah like dre said, dont go above 3500-3800 RPM when cold. There, problem solved.

 

Thats not the point!
I know all the things you are and are not supposed to do.

By "after it warms up" I mean within the first 10 minutes!

This shouldn't happen like this.

What could be causing this "missing" but not after about 10 minutes.

I have a sneaking suspision that its impacting performance even after it appears to go away.


I cant beleive I just got a bunch of "well, dont do that" to a problem.

 

well, don't do that! j/k ok realy it's your tps it's prob. not affecting performance after it's warmed up but what you can do is adjust it. how are you adjusting it? w/dmm or lights? if with lights then you can't adjust "properly" i've been fighting this for a while mine would and still kinda does the same thing but when it was warm it would buck like an sob at high rpm. what i did was adjust all the way down drive tunr up until the bucking at high rpm went away and then you can tune for drivability and hesitation. what your getting is hesitation because the signal isn't good when it's cold.

but, like i said this IS NOT affecting performance after your car is warm the reason it's not wanting to pull or "hesitate" is your not supposed to go that hig when the car is cold.

 

i had my s-afc tuned with too much fuel, it would do this , turned down the fuel and now it doesn't do that. True u aren't supposed to drive like that, but when you are lat for class at 8:30 in the morning, **** happens

 

Okay, let get this straight...

Im not DRIVING like that.

I BUILD these cars and usually NOTHNG stumps me on these cars, but I have to test the HELL outta this car before i sell it.

I noticed that the hesitation happens for about 10+ minutes.

This is WAYYYY beyond the normal time you wait for driving the car.

Somthing is wrong.
I have adjustred tps.
The same as I have for ove 15 cars now.

I build these cars full time now since getting laid off.

SO, I am just putting the car throught its paces prior to selling it on the auto trader.

If its not the TPS, then what ELSE could it be?

Ill FIDDLE with the tps, but its simple to see that at 3999 RPM the car runs fine, but at 4000 RPM, it starte to shake and sputter.

It would seem that as it switches to its internal fuel maps, some sensor is not performing tight to make the fuel map operate right.

This isnt Limp mode is it?

Is this car in limp mode until it warms up?!!!

How freaking ODD!

 

is it running rich?

 

Maybe mineral spirit fumes in the intake. J/K

Have you checked the AFM for crap?

 

i have cheked the AFM, its fine, its only missing above 4000 during the first 10 - 15 minutes.

 

I had that when my plugs were bad. When I got the car, the leading plugs were on the front rotor and the trailings were on the back. New plugs in correct location helped a little, and several bottles of FI cleaner along with an ATF(using Seafoam) treatment fixed the rest.
Might be a dirty injector? Plug wire resistance? Hows the fuel pressure/filter? Spark? Vacuum leaks? Any ECU codes? and all that other simple stuff?

 

I rebuilt the intake system and ultrasonically cleaned the injectors.

I could replace the secondaires, but only if this missing is because a injector is not firing right until warm.

During this "mising" period I cannot get the rpm over 7500.

The AFM is fine
the plugs are clean
the compression seems fine. (I checked it cold.)
the thermosensors and neutral sensor is good.

I will have to replace the secondairy injectors with more from my stock if this continues.

I'll see if that fixes it unless someone else has a better idea.

 

Check the resistance of the coils COLD and HOT,

 

Boost sensor? Orifice missing? Just a thought.

https://www.rx7club.com/forum/showth...456#post675456

 

hmm... a querry indead, what are you using to check the tps? also try replacing the resistor with a known good one.

 

What resistor?

What are you saying?

 

the resistor is the whole screw part that you use to adjust the tps. if the resistor is bad it will give false readings for the tps. this is why i asked whether you were useing the lights or a dmm.

james

 

oh ..
the tps is good

 

did you test the coils yet?

 

Yes.
I replaced them with known good ones too.

 

Got access to an o-scope to check ignition patterns?

 

yes, i used it. the patterns seem fine.

 

OK latest brain storm. Change the O2 sensor, it could be providing bad input to the ECU.

 

I did