I asked some peeps about my car not willing to go past 125 and after looking up a whole bunch of places all i see is a 110 limiter on other cars, my 350 TPI runs 100% does a 125 limiter exist on a '89 350 GTA? or is something bothering my motor b/c it accellerates from 100-120 in a snap but no further and in the tech articles it says tpi' don't have limiters, I'm confused?
I found nothing with a search.

 

Maybe your just topping out?

I have taken my car past 125 without a problem. And believe me I won't do that again for a looonnnggg time.


Why r u so interested in going past 125 anyways?

 

i got a similar issue, my car accelerates and then at exaclty 115 cuts out...it is a tpi but it muct have a limiter, i dunno, try disconnecting the wire in the harness from the speed sensor to the computer and u will find out...i think its wire 10 in the A harness...might be brown...cut it!!!haha jk, but look into it

 

Your car doesnt have any speed limiter on it besides your right foot and the power output of your engine. Sounds like something is amiss, it should run past 125 with no problem. The speed limiter on all the TPI chips I have seen is set to 254MPH, somehow I dont think you'll hit that one.

 

for what reason would the engine clearly stop accelerating at 115 mph? any ideas?

 

I've checked everything and can't find one thing amiss, timing is not an issue because I set it to factory spec and used my timing light to check if it's outta whack and so far ok, and yes i did disconnect the tan wire to keep the computer from toying with the timing to get a proper reading. but question is the thing goes from 80-125 in a heartbeat with plenty of beef left in the powerband to go way higher... stock rear 3.23's also, and I am very interested in more than 125 mph, just to see what I can really max out at!

 

oh i forgot to mention my car is almost stock so I no torque drops off in the upper rpm's and another thing the only place to go that quick by me is on a bridge thing (no cops) that has a slight incline but not a hill so maybe that was it?

 

that has nothing to do with it..the incline deal...your car should hit around 140

 

my speedometer is off enough that I "top out" at 125 on the speedo. But considering I'm doing 70 mph at 58 on the speedo...and it gets worse and worse the faster I go...I should be hitting the good ol 140.

 

speaking of which...anybody think it could be the VSS? Or how does this car determine what speed to send to the speedo?

 

It is you buddy. I have an '89 GTA w/ 350 and have no prob past 125. What gears do you have in the rear?

-Schultzy

 

I've got the stockers...3.23 pretty sure. Whatever it is...3.23 or 3.27 can't remember such small numbers. I've been thinking it's the Vehicle Speed sensor...but it could be something I haven't even considered.

In the mean time between repair periods, I've had my car timed by police I know so I can stay within acceptible limits. Just imagine if I did 70 on the speedo (which is past 95 mph) and got caught. I'd say....officer I was doing 70. He'd just laugh at me.

 

then WTF? the damn thing is a rocket and, i dunno wtf is going on maybe it was just something off on the car, besides it was a while ago that i did that when I bought the car and it was when the motor ran rich and drank a tank in like a day. I've done alot of maintenance on it and stuff like that, before i would pull out the plugs and they would be black as a lump of coal, now they are nice and golden brown (like a nicely toasted marshmellow ... mmm) and doesn't take a tank down for a couple of days. I've had the car for 10 months and have come a long way in maintenance, my gta was neglected up the @$$ from the body to the brakes (one of the pads dug in the rotor now it has 2 grooves in it) the dude who owned it said the motor was rebuilt at 100k and when i got it it was at 116000 and when I took it home the 1st time the oil was low low, i mean low and thick and black like a varnish. The guy told me every $ he put in it he put in the motor to upgrade it. I've done everything from oil to brake pads to the diff oil, all that's left is my idler arm and fuel filter (original rusted as hell!) so maybe back then the motor was too sick to give it it's all, the next opportunity i have to got passed 125 i will (hopefully there won't be cops around) bottom line the whole time i thought it was a speed limiter because I read a tech article somewhere that F-bodies had limiters I didn't know TPI's didn't or rather they were set to 200+ so maybe it was just an untuned motor... I feel like an *** if I only had $$$ to build a custom motor (i helped do a mitsubishi 2.6 turbo once) I learned alot from that... thanx for the input. As for the 115 mph prob, dunno man maybe a good tuning would help.

 

It's probably your coil. These coils are worked hard in these cars. There is a way to test it and see if it losing power at top end, but I don't remember how. The limiter for the 350 is initially set at 147mph, any aftermarket chip is above the 240 something mark.

 

I have seen a few TPI proms with 115 and 125 limiters in them. Drop me an email with the broadcast code you have on your memcal/prom and I can probly get a copy from ftp.diy-efi.org and then see if it has a limiter in it. I'm at work right now though.

If you post the Broadcast code(the 4 letter alpha code) somebody else may be able to help out also.

Brendan

 

m i'll do that today, but a little later because it rained over here and everything is wet.

 

here are pics of the prom and memcal #'s

 

memcal pic 2

 

prom #

 

and other #'s on the prom if they are any use

 

the APYU chip has no speed limiter (set to 255mph)

 

This is not true. Almost every 350 that came in thirdgens had no speed limiter. The ones that did were normally set to 115 or 125, but it is extremely rare to see TPI with a speed limiter.

 

IROC89, Thanks for looking that up, I just got home from work and didn't get to it yet.

 

My Rs had a limiter at 115....

The Formula does 145 no problem...

 

hey, i wired up a bypass switch from my speed sensor to my computer...before i couldnt go past 115 and i switched it off at 110, my rpms when immediately from 3400ish to 4700ish and my car coulnt accelerate, then i switched it back on and i could go over 115, got to about 120 something and i didnt want to f*ck up my car so i stopped, i wonder why it did this...my car does have a speed limiter on it at 115.

 

Sounds like you are finding the typical GM 700R4 3-4 upshift problem. At wide open throttle, the transmission will not shift from 3rd to 4th, so it will stay at redline in 3rd which is around 125mph depending on your rear gear ratio. Try accelerating to 125mph and then slowly back off the gas until the trasmission shifts to 4th(about 3/4 throttle) and the car should start accelerating again. B&M makes a valve to help this issue, but does not competely eliminate it. The GM kit does fix the problem, but locks the transmission in overdrive at any speed over 45mph, so it's pretty much a 3 speed auto with a manual overdrive.

 

I did it just now coming home it went to about 132 mph it was just a badly tuned up motor the engine easily went passed 4800 around where it got stuck last time and kept pulling then i let off.

 

Aahhhhh, good old tune up!

;-)

Glad you got her running right bud.

Later,

-Schultzy

 

I've read in previous posts that the speed limiter was set to the speed rating of your original tires, S H Z whatever as a safety feature. The computer would start dropping fuel pressure or timing at whatever it was limited to to keep you from going faster than the original tires were rated for. It keeps the auto mfg's from getting into trouble. I heard that 254 was the highest number that could be programmed into your chip to effectivly 'eliminate' the speed limiter. Hope that makes sense.

 

255 is the highest setting that you can set for fuel cut off speed. That’s what most TPI engines are set to stock. The computer turns off the fuel injectors when it hits the speed limiter setting and turns them back on when the speed is less then or equal to the resume fuel setting in the ECM. The highest possible number is 255 because are computers in our cars are 8 bits computers. There are 256 possible numbers that can be made with 8 bits using base 2 (0-255).

 

i have had my iroc with a 305 tpi doing 130. thats pretty scarry on a road maybe it wouldnt be to bad for a highway but it is really scary.

 

And to all the rest of you Bonneville Types,

I hope That when you eventually hit a Pothole or your Wheel bearing Fails, The only person you Kill is yourself.

Keep it on the track. Triple digits in a brand new Z06/M3 Ect is sketchy enough. Doing it in a 15 year old car with Soft stock suspension is insane.

 

soft? my car barely tilts when i push it hard around turns, i've taken crazy turns with it and it is stable as any other car at high speed.

 

i have taken my car up to 155..... got to 130 real fast then took a bit to get all the way up there.... had a friend in alother car keeping pace with me in a L98 TPI vette with a digital speedo i might have been able to get it to 160 but the RPM'S were screaming.... mabye thats why it started knocking after that.... lol

 

I see we have got a couple of future Darwin Award Nominee's here.

 

just speed junkies man. As soon as one of us strap a rocket to our cars....then we'll be Darwin candidates. <<< those teeth will be how they identify me when I'm halfway in a mountain!!! :sillylol:

 

yea i must agree my suspention is pretty stout for stock.....