Kyler_89RS

I can’t really start the car without giving it some gas. When it’s warm, I can start it without the gas most of the time.

Replaced
- IAC Valve
- PCV Valve
- CTS
- Starter + Battery

I posted a video of it too.

Link:

Reddragon88gta

Not very familiar with TBI, but how is your fuel pressure and when was the fuel filter changed last?

Kyler_89RS

Fuel pressure is 9-10. Fuel filter was changed with a K&N a year ago.

Reddragon88gta

Have you tried adjusting the IAC? I did see that someone runs a stronger fuel pump from the 89'Turbo TA and he claimed it did the trick(bottom link)

https://www.thirdgen.org/forums/tbi/...djustment.html

https://www.thirdgen.org/forums/tbi/...gas-start.html

Kyler_89RS

I connected it. Turned key on. Disconnect. Turned key off. Connect. Didn’t do anything. Acted just like it did before.

Is there something I’m missing?

Reddragon88gta

Sounds like you got it, its pretty straight forward to adjust IAC. This seems like a pretty common problem with TBI cars too. Other than it possibly needing ignition tune up stuff or a worn out distributor replaced I cant think of much else.

Schurkey

A scan tool to look at the data stream. Might be nice to see what the computer is telling the IAC to do. I'd want to know what temperature the computer thinks the engine is as, when "cold". And of course, verifying MAP sensor, fuel trims, etc.

Kyler_89RS

I don’t have the tools to look at the data lol. I should probably do that.

I’ve replaced the CTS, too.

Schurkey

FIFY.

You could replace the CTS a thousand times, and still have a problem...if the wire harness for the CTS has failed. You'd see this right away with a scan tool; you'd spend half-an-hour or more (probably more) trying to figure this out with a multimeter and breakout box, and you'll grow a beard trying to do this with the multimeter but not a breakout box.

The ONLY way to do proper diagnosis in a reasonable time frame on the computer-controlled systems, is with a scan tool or similar data-stream viewing tool. "Codes" are helpful; data stream is ESSENTIAL for diagnosis.

Kyler_89RS

What tools do I need to do it? I’ve seen the cables to plug the obd1 plug into a laptop. Should i get one of those cables?

Schurkey

I've heard of, but never used the software-based "scan tools". They seem popular on this site, but I've got zero experience with 'em.

When it was me, I bought an elderly Snap-On MTG-2500. These are so old now that I'm not sure I recommend them any more. My scan tool is probably older than half the people on this forum. Mine has software good for model-year 2006, after that I can only use "generic" OBD-II.

If I ever buy a car newer than 2006, I'll probably upgrade my scan tool to a newer Snap-On model. I've toyed with the idea of getting a cheap one and trying it out...and then I need the Snappy to communicate with ABS, or an instrument cluster, or whatever. Most of the cheap consumer-grade tools only do engines; you pay extra just for ABS or maybe Transmission access; and they don't offer instrument cluster or air bag communication at all.

Better to buy a used "professional grade" scan tool than a new "consumer-grade" tool.

henryd3

iTrader: (128)

Did you do all of this?
https://www.thirdgen.org/tpimod2/

Kyler_89RS

I'm going to revive this thread again.

So the car is still doing the same thing. Has a hard time starting when cold and I've noticed crank times are much longer on initial startup for the day. When it's warm, the crank reduces dramatically, but I still have to use some gas to persuade her to start. Not as much as a cold start though.

I've replaced the starter, battery, IAC, PCV, spark plugs and wires, fuel pump, fuel filter, O2 sensor, CTS, TBI rebuilt and cleaned, injectors cleaned and no drips. That's all I can think of atm.

Any other ideas?

Schurkey

Does the fuel pump prime when turning the key from "Off" to "Run"? Pump should run for two seconds, then shut off.

If the pump won't prime, you have problems in the fuel pump relay system, which includes the ECM, wire harness, and relay. That means extended cranking time because the fuel pump won't run until the oil pressure triggers the oil pressure bypass switch. The oil pressure switch then powers the fuel pump.

A fuel pressure test would confirm lack of fuel pressure when cranking, before oil pressure has tripped the oil pressure switch.

All of this is common as dirt. Sometimes, it's as easy to fix as replacing the relay. Other times, the problem is in the ECM or the wire harness, including loose connections where the relay plugs into the harness.

Kyler_89RS

Pump does prime. I tested fuel pressure before the replacement and it was around 7. After replacement, its up to 13. Replaced with an ACDelco pump

Schurkey

Connect a scan tool, look at the sensor data, and computer outputs during cranking, and while running. I'd be especially interested in coolant temp, TPS, MAP, cranking RPM, but verify EVERY sensor (O2 has to be hot to verify)

If this isn't a fuel pressure problem--and you're saying you have fuel pressure BEFORE cranking the engine--then the answer is in the data stream.

Kyler_89RS

There is pressure before cranking. Ill have to buy one of the ALDL cables and look at the data.

PapaRoach3

Thanks so much for that I'll get back to you thank you