xxx3man`

iTrader: (5)

I am using the stock TPI setup in my 89 iroc. I am having a problem with it idling when first starting. It doesn't start unless I give it gas when it try's to start. Then I have to keep my foot on the gas for it to keep running. Once i drive it a little it will idle but at like 600rpm when it's set to idle at 900rpm not stock setting. When accelerating it will start to pull then drop Rpms then kick back in.
I've tryed to reset the ECU and readjust my tps sensor using a data log program. This all started when I found out my iac valve was loose so I tightend it.

gta_knight

Maybe the IAC is damaged if it started right after you tightened it up, id take it out and check it, the pintle might be stuck or broke.

Ive had my fair share of idling issues with my 5.0, i eventually got round to changing everything, the IAC, the TPS, Ignition module etc etc and it was running smooth as silk before i pulled the engine to install the 5.7, but ive got all my new parts from the 5.0 to go in the 5.7 so im hoping for more of the same

jtsk

iTrader: (3)

xxx3man, my 92 z28 5.7 TPI is doing the exact same thing on starting. It is driving me to the point I want to get rid of the car. EVERY single sensor, IAC, TPS, etc is brand new and it still won't start unless I give it gas and then have to work the pedal or it won't run until it is warm. I am hoping someone here has the answer because I am ready to sell it.

85Special

Reset your IAC. Key on, disconnect IAC, key off, reconnect IAC, key on and start. You'd be surprised. It resets the computers closed position.

jtsk

iTrader: (3)

85special I have done that as well to no avail. Is there a certain amount of time to leave the key on before disconnecting the connector?

xxx3man`

iTrader: (5)

jtsk dont go off the cliff here and sell that car i am sure its just some settings from the idle screw and the position of the TPS something like that. will have to try the reset of the IAC

darbysan

I have found in the past that it takes a couple of iterative attempts adjusting both the IAC and the TPS to get them in line. They are a little finicky, and each setting will change the other a bit.

Here's the procedure for IAC and TPS adjustment. I thought there was something in there about shorting the ALDL connector before setting the IAC, and it is.

https://www.thirdgen.org/tpimod2

xxx3man`

iTrader: (5)

ah that will help will have to try that

jtsk

iTrader: (3)

darbysan thanks, I'll give it another go once the weather here clears, assuming a tornado doesn't blow through.

GTAman

iTrader: (2)

let us know how it works out. i'm having idling troubles myself!

xxx3man`

iTrader: (5)

I just tried resetting the IAC and adjusting the idle screw that seems to have helped a bunch. It doesn't like the cooler weather so I'll have to drive it around when I have some time. The only thing I have to adjust is the TPS that should help it run much better

jtsk

iTrader: (3)

ok, I went through the IAC adjustment again and it still won't start without me giving it gas. However it does seem to run better, if not slightly high on rpm's, at a stop light. I guess that's an improvement. Will drive it a bit as is to see if the starting issue works itself out.

3.8TransAM

Take a look at the injectors and regulator.

Similar symptoms to what u described can be attributed to those as well.

xxx3man`

iTrader: (5)

Ah funny you say that I did loose the adjuster screw for the regulator but checked the pressure and it's at 42psi

jtsk

iTrader: (3)

@3.8 will do. thanks!

jtsk

iTrader: (3)

ok, checked the injectors and all of them are at 12.5 ohms. They are Bosch lll's and I believe this is normal for those. Haven't checked the fuel pressure yet, but will. Still won't start without giving it gas. .Runs ok other than at starting.

xxx3man`

iTrader: (5)

fixed that pressure reg got the pressure up to 49lb and that helped

jtsk

iTrader: (3)

Mine is running "somehwat" better, but I think my no name IAC is bad. I bastardized the old IAC motor with the pintle out of the new one and it helped a little. Going to replace the IAC with an AC-Delco unit this time around.

jtsk

iTrader: (3)

Update: still having idle issues, especially at starting when dead cold. Other times the idle wonders between 500 and 1000 rpms. Still going to replace the IAC with an AC-Delco part, but it will have to wait. My tranny in my s-10 crapped out, so guess where the dollars for car work are going???

norcalz28

iTrader: (13)

Sounds like a vacuum leak. What is your MAF sensor reading? Anyway to get live data? Have you set minimum air? Don't forget to do this when you adjust timing or dial in the IAC. I would also adjust TPS. My car ran very bad last summer, and I checked all my bases. Well it only ran bad once the car was warmed up, and going, or trying to go into closed loop. Checked the o2 sensor and it was physically coming apart. Had hardly any miles on it. Replaced it and that took care of all kinds of driveability issues.

Will

GTAman

iTrader: (2)

mine still idles like crap too. I set minimum air and adjusted the TPS when warmed up, drove it the whole day,let it cool down completely, next day went to start it fully cold and had hard start. it only idles at where i set it to (500 rpm) at all temperatures. it doesn't idle up at all and it should start high at cold start and work it's way down as it heats up. TPS tests good, IAC is new (this is the second one i put in, this one is a better quality. the first one was good too. I have an IAC tester). Just got my AFPR. will install on weekend. Thinking of getting a set of injectors to rule them out, as i reused the ones that came with the engine. really starting to get frustrated with this. how many times does it take???

rusty vango

ah, the joys of owning a TPI car.it seems as if they require CONSTANT dinking with.part of our problem lies with the questionable quality of replacement parts (think china) and some of it is that our cars are coming up on 30 years old. and yes ,changing ANY one thing effects EVERY other thing. which leads back to the constant dinking with them.i cant count the times I have just wanted to rip it all out and get a carb and be done.i can tell you all from my own experiences with my 86 IROC .DO NOT BUY auto zone anything! same goes for advance. even the parts that you buy from the dealer are Chinese.i have had the best luck so far with BWD select parts that I buy from my local oreilleys. a factory service manual and more patience than jesus .is absolutely essential. lap top data logging is a fine way to see in real time what is happening. and it cuts down on WTF!! moments considerably. hats off to anybody who voluntairily chooses to try and drive one of these cars. and ,,boy ,,I feel your pain

alex722607

iTrader: (3)

I am having the same problem. I have been trying to get my car running correctly since late May. It started with leaky injectors, so I replaced them with Bosch III's. Then The IAC was replaced. Afterwards I realized that my esc stuff was still left over from the 305. So I recently changed my ESC, knock sensor, a Bosch O2 Sensor, and a coolant temp sensor for good measure.
When my IAC kept going down to 0 when in park or nuetral, and a vacuum leak was ruled out, my dad tried adjusting the idle stop screw. I got better IAC readings, then I had to check the base timing again, because it sounded funny. Turns out that after changing the position of that screw, the base timing went from 6 to 12 (I checked before he adjusted the idle set screw). So I took it for a ride (to get gas) and for it to go into closed loop. I came back and plugged in the scan tool. Block learn was 160 -- go figure. Every time she wanted to stall, the iac number decreased. (But it doesn't bottom out at zero anymore.)

I am so sick of this, I think I am going to find myself a donor car and grab an LS1. However I am not giving up just yet so any help is greatly appreciated.

jtsk

iTrader: (3)

Norcalz28, I don't have a maf, mine is a map car. I have checked, double checked, and rechecked and I cannot find any vacuum leak, as I thought this was the problem too. The bastardized IAC has helped, but by far it still isn't right and just today as rusty vango stated, I considered carbing it so I could at least drive it. FRUSTRATING! Amen on the crap AZ ***** parts. Lesson learned on that one!

jtsk

iTrader: (3)

Problem solved... traded the car for a Jeep.

xxx3man`

iTrader: (5)

Well I guess that's better then sending it to the junk yard and having it crushed lol

jtsk

iTrader: (3)

True. Just got burned out on it. Was wanting a Jeep for a while, found a guy wanting a Camaro, so it was a good trade for both of us.

xxx3man`

iTrader: (5)

Ha yea I get that. I've been burnt out with mine for the past 10 years but still love it. But jeeps are the best I have a wrangler daily driver can't beat two cars that can got topless

xxx3man`

iTrader: (5)

so was trying to set the TPS and on my scanner its reading .14-.04 and thats super low. i was trying to cross check that with a volt meter but i cant get any kind of reading with the meter. how do i check the TPS with a volt meter.

rusty vango

you need 3 wires to make a test rig. you plug them in to the TPS and take your reading

xxx3man`

iTrader: (5)

would it work by jumping a paper clip between two of the ports or does there need to be actual power flow through the sensor

rusty vango

yes , you need to have all 3 wires hooked up. I guess you COULD use 3 paper clips. you can adjust it with the engine off, but key on. im not sure on your year of car which wires you should take your reading from. mines a 86, yours could be different.

MadMaro

LLH.....i guess I'm not overreacting. My 88 tpi with 400 bottom end makes me wanna give up, until i fix one problem and here the 400 thump. Then...there's something else fkn up!

rusty vango

the TPI mantra..... its not a Honda, its not a Honda, its not a Honda.....ommmmmmmm

alex722607

iTrader: (3)

So I think that my engine is on its way out. I keep praying for it to finally crap out. I think I am the only one on the planet that is praying for a blown headgasket so I can justify an LS1 and the corresponding hole in my wallet.

I spent over $400 this summer on trying to make it run right. I refuse to spend any more money on it besides an oil change every 6 months and gas. (Oh and ofcourse coolant) All three keep disappearing.

Let's see:
Bosch III injectors - 150
Gaskets (three different times) - 90
Cold start delete - 24
plenum and runner bolts that suck - 24
fuel pressure regulator diaphragm - 50
ESC module - 70
knock sensor - 30
02 sensor - 12
coolant temp sensor - 6

(So actually around $450. Could have put that towards weatherstripping and carpet)


My dad doesn't want me to ditch this tpi and SBC because he says that it won't be stock. Technically it is not stock now because it has a 5.7 and not the original 5.0. He also said the LS is too much power for this body. However I think that the LS secton of this forum disproves that notion. This car has had 3 different SBC's in it and twice as many 700 R4's.
I want a nice driver.

rusty vango

ls ANYTHING is serious money to be throwing at your car. done right .they are $10,000 on a good day.ask around, im not off the mark. it is not as simple as drop it in and go. the whole car needs to be brought up to the power a LS gives. but ,hey .maybe you have a bottomless wallet. and who am I to know? of course there are people who have that much in a gen 1 sbc with a TPI. but take a step back, and look at what you have done to this one. what DIDNT work? why? what are the main problems? and above all. WHAT EXACTLY do you want it to be? I know how you feel, really, I have north of $12,000 in a $500 car. but im a crazy ol man. so I use that as an excuse.

xxx3man`

iTrader: (5)

is yours one complete sensor or is it the sensor with wires coming out to a connector

alex722607

iTrader: (3)

Okay let me elaborate: no I don't have a bottom less wallet, what I have is a gorgeous car with an untrustworthy engine. I get a phantom trouble code and I try to find the cause like with a code 36 maf burnoff failure. I tore half the car apart and found no problems. The occasional stalling and shaking at idle caused me to suspect leaky injectors which was confirmed by a fuel pressure test. New injectors did not solve it. Now I suspect a vacuum leak and I have inspected all the possibilities to no avail. My transmission has also been a thorn in my side. For instance this car has had around 6 or 7 and each have had their issues. What do I want, a nice driver that is reliable. I want to spend money once and not keep spending money as parts continuously fail.
What makes me think I will have better luck with a new drivetrain is the fact that I will have the benefit of new technology, better diagnosis and so on.
Every time I open the hood to work on it or rather every time I had to in the past 3 months, all I could think about was ringing the neck of the person who designed TPI. Sure it has its perks, but not for me. It is a little embarrassing when this thing stalls at a light or stop sign (especially with a passenger in the car), and driving with two feet is getting old really fast.

As for LS1, well I am not going to pour nutty money into performance. I am 20 and I love this car to death, the SBC and accompanying TPI, well they get the boot.

I do not intend, nor do I want this thread to become about L98 vs. LS1, a thread was already closed and it didn't solve anything. I expressed my personal feelings because I needed to vent somewhere. Getting pissed off and yelling just doesn't cut it anymore. If you like TPI, more power to you, my issue at idle did not get resolved. And I am already buying LS parts.

Hope I didnt stomp on too many toes.

jamon8

iTrader: (3)

I don't want to hear anything negative about tpi until you buy a helms manual and really learn to fix the car right.

alex722607

iTrader: (3)

Not to chum the waters even more, but I have a GM manual. Thats whats got me chasing my tail. Plus my dad knows this setup like the back of his hand. He is stumped too. Every time I open the hood he asks me when I am going to junk it.
Again I am not trying to create waves, but its my experience. I know there are die-hard tpi guys on this forum, but I want nothing to do with TPI. Sorry, With that said I am going to stop ranting. Sorry for any ruffled feathers.