problem!!!

[sleepyalero]

Okay so sadly my car was in the rain. Merged onto highway my wheel bearing lights kicked on. No biggie. Got closer to my house idle at a stop sign was 1000 rpm. Shut car off, restarted it hesitated I had to give it gas to get it fired up. Now the rpms are drastically low. Wheel besring lights are off.

It died a few times on my way home to where I just turned flashers on and ran stop signs to get home. Car is now running in my garage. I thought water got in the intake. Not that. Cleaned maf to make sure anyway. Car still running weird.

- oil pressure okay.
- a/f is okay till car stumbles a bit.
- volts is at 11.5 to 12 v running.
- idle is at about 500-575.

Whats the issue here? She waa running fine earlier. Could it be sign of alternator going bad??? No service lights are on. I plan on hooking up hpt to see if there is anything hidden. No sensors are unplugged. Nothin. Im stumped atm

I know I probably wont get a answer tonight so ill try to start her tomorrow as well to see if she acts fine or still has an issue.

[sleepyalero]

Okay scratch my alternator plan. I thought my alt was going out awhile back and was wondering if it was struggling and finally on its last limb but I think it's okay.


After doing a log on HPT for about 10 mins running through all things like TPS voltage, %, injector stuff. Evap and everything you could possibly choose to put in the table. Started the car... died on me 4 times during the log then finally I got it to hold its self up while I could watch all the numbers. Everything looked fine.

But then I came accross IAC position. Its stuck at a solid 255. Doesnt go up/down when giving the car gas. So im assuming I have a bad IAC. Am I correct?

Im pretty postive on it. Cause I know in previous logs it moved. Lol

[[ion] C2]

most likely

my iac was goofy after going through deep water once

[AleroB888]

But then I came accross IAC position. Its stuck at a solid 255. Doesnt go up/down when giving the car gas. So im assuming I have a bad IAC. Am I correct?



Could also be a defective (open or shorted circuit) wire plug going into the IAC.

Was it stuck at 255 while the engine was running?

[S8track16]

You're getting 11.5-12 volts when the car is running? It should be around 14.4-14.8.

[03glgold]

You're getting 11.5-12 volts when the car is running? It should be around 14.4-14.8.

This....might not be gone completely but have a bad diode...we got supremely lucky in my moms suburban on the way home from spring break...we were just abouy finished with one hundred mile stretch with no towns when the diode gave and were able to stop and put on a new alternator at the last town before another hundred mile stretch of nothing

[zzyzzx]

You're getting 11.5-12 volts when the car is running? It should be around 14.4-14.8.

idle is at about 500-575.

Voltage reading should be taken at 1000-1200 RPM with the rear defoggers, A/C, and stereo off.

[Kalimaze]

When my car is at idle with stereo and subs a booming headlights on the lowest i have ever seen my volts drop to was 13.8.

[fisdad]

yeah buddy you need to get your alternator checked and most likely an IAC. I would also keep your CPS in mind if this doesn't solve your problems.

[sleepyalero]

Sorry I should have added some stuff.

Car runs fine if I hold pedal from 850-5000 rpm. I think the iac is the whole issue possibly. IAC was stuck at 255 running. Yes.

The hell is a cps ryan lol


Voltage is only low at the 500 rpm area. Give it gas it goes back to normal. Then back down once it tries to idle or it dies.

[[ion] C2]

cps = crank position sensor

probably IAC

[a.graham52]

Yeah, rpms that low, alternator can't put out proper voltage.

[sleepyalero]

Figured the cps out lol and ill replace iac In awhile and find out

[Redog]

I vote IAC, but that voltage is LOW!! Should be that with the car off, not turned on and running :eek:

[sleepyalero]

Oddly enough when key is in ON position. Not running. Volts are at 12.

[S8track16]

Oddly enough when key is in ON position. Not running. Volts are at 12.

Does the voltage change when you turn the car on? Otherwise your battery will just be drained.

[a.graham52]

Voltage is only low at the 500 rpm area. Give it gas it goes back to normal. Then back down once it tries to idle or it dies.

500rpms is too low for proper voltage !

[AleroB888]

....- idle is at about 500-575.



The target idle RPM in your PCM calibration is:

675 RPM, from 176 to 212 degrees ECT (Engine Coolant Temperature).

disconnect battery swap out the IAC, try to start it;

still no workie, check continuity on plug wires.

[sleepyalero]

Does the voltage change when you turn the car on? Otherwise your battery will just be drained.

Volatage is at 12 in ON position. Car running 11 volts.

500rpms is too low for proper voltage !

Correct. I figured as much.

The target idle RPM in your PCM calibration is:

675 RPM, from 176 to 212 degrees ECT (Engine Coolant Temperature).

disconnect battery swap out the IAC, try to start it;

still no workie, check continuity on plug wires.

I will in about 2 hours!

[Nas Escobar]

Oddly enough when key is in ON position. Not running. Volts are at 12.

Volts should be at 12.6 when on the On position, engine off. With the engine idling, the lowest it should be is 13.0, but typically the volts should be 13.6-14.2. When you replace/clean the IAC then check the volts again... I have a feeling the Alt might be on its way out.

[fisdad]

Meh... Time for a rebuild. No time for all this diagnosis bs. Two words... TURBO TIME!

[sleepyalero]

Off its sat at 12v for years.

[Nas Escobar]

Off its sat at 12v for years.

That's normal dude, I meant when you use a calibrated volt gauge. I bought one of those, and it always read 12.6 in my car.

[sleepyalero]

I just have a prosport volt gauge in my car. I mean in summer its as high as 12.5 ish. But cool/cold nights depending how long it has sat. 11.5-12

[Nas Escobar]

I just have a prosport volt gauge in my car. I mean in summer its as high as 12.5 ish. But cool/cold nights depending how long it has sat. 11.5-12

That's interesting, my car wouldn't drop below 12.4 unless I was opening/closing a window.

[MMGT1]

Connect your HPT and start a scan, have your lap top out window under hood where you can watch the scan as your under there. With the engine running, unplug and plug in the IAC and see if it responds at all. If not, move wires, follow them back as best as you can and wiggle them while watching scan and see if it blips. This should narrow down whats happening there bud. If wiggling the wires has no effect then replace the sensor and see if its gone. Grab one off another car man to test before you buy!

[sleepyalero]

I had a buddy owe me 40 bucks. Just had him get me a IAC. Will test soon and report back. If anything ill try your method paul. Thanks for stopping in buddy!

[sleepyalero]

Well its FIXED!!!!

It was indeed an IAC. Im letting it warm up to temp to be sure. But shes idleing at 1050 right now. (Cold start) so we will see if she gets normal. But shes doing fine so far. :)

[MMGT1]

Nice man, glad you got it! The reason I was suggesting a "tester" before you grabbed one is that most parts stores wont allow a return of an electrical part. At the dealership if you bought that from me I would not be able to take it back if it wasn't the problem!

[sleepyalero]

Yeah I know. To me it reading a constant 255 in HPT made me feel 95% sure it was that causing the issue. Purs like a kitten again :)

[[ion] C2]

most parts stores wont allow a return of an electrical part. At the dealership if you bought that from me I would not be able to take it back if it wasn't the problem!
That's why you tell them you didn't install it and instead figured out the problem was elsewhere.

[sleepyalero]

Exactly haha

[AleroB888]

Nice man, glad you got it! The reason I was suggesting a "tester" before you grabbed one is that most parts stores wont allow a return of an electrical part. At the dealership if you bought that from me I would not be able to take it back if it wasn't the problem!

On the other hand, after a while you will have a collection of spare sensors to carry under the seat ;)

[MMGT1]

On the other hand, after a while you will have a collection of spare sensors to carry under the seat ;)

LOLZzzzzzz......

[negolien]

Glad ya got it figured out

[Chris2000]

After reading a few lines I was going to say IAC. Those things are made so terribly. Start there.

Edit: Read more and found you fixed it. Good to hear.

[sleepyalero]

Thanks guys. Very happy shes fine. :)