brentbrowning01

Hey ya'll. I know it's been a while. My Z28 is sputtering when I crank it. It doesn't doesn't do it as bad when it's first cranked but as soon as it warms up it starts. MAF is good and gas is good. I"m at my wits end. Any help or suggestions? Here's a link to a video I made of it sputtering.

Thanks!

shoebox

Scan to see what is causing the SES light. That would be the first thing.

brentbrowning01

Ok, so apparently my pcm thinks my coolant level is -40.. Why would this be?

GaryDoug

It means the engine is being flooded with fuel because the pcm thinks the temp is -40. You may be able to start it by holding down the accelerator pedal while cranking. Either the engine coolant temperature sensor (on the water pump) or its connector or wiring is defective. Replace the sensor and try again.

brentbrowning01

GaryDoug, Attached is the CSV file of my scan today.. What's weird is my SES light was on but the scan didn't give me any codes. DLOG-trans-2016Jun06-003500-2G1FP22P0S2111881.csv If you see anything out of whack, feel free to point it out. Thanks for the help and thanks for making such an awesome program!

Injuneer

Setup may be wrong. The data log is very short, and only the first nine columns have numbers, the rest of the columns are all zeros. No labels at the top of the columns.

brentbrowning01

Yeah that's what I was thinking. It has the columns on my computer... Oh well. Something else to fix..... Grrrrrrr

Fatdog2

Previous posts here a long time ago suggests this could be you idle control valve,on the side of the throttle body.(aside from the egr valve or lines going to and from it.)As Injuneer says the idle should be less than 800 rpm's.There are a million icv valves out there but I would go ac delco.Might pull your old on off and look at it.I think there is a test for it but I dunno.Could be the gasket for the icv as well.If it looks like you know what,I would replace it especially if it is the original one.Sorry for the long post.Please post back asap.My02
P.S.Might as well spray the throttle body with throttle body safe spray while everything is opened up anyway.Hope this helps(Idle air control valve).

Injuneer

Not sure where you got that I said the idle speed should be less than 800 RPM, or where there is an indication that his isn't.

Target idle speed is variable, based on coolant temp sensor. The target idle speed for a very cold day (screen shot indicates -40-degF for coolant temp - we know that's wrong) can be as high as 1,200 RPM in neutral/800 RPM in gear for an A4. Once the engine is warmed up (at least 176-degF coolant temp), target idle speed is 650 RPM in neutral and 550 RPM in gear for the A4.

In the screen shot, the engine is not running, so it shows the default values for target idle speed (3,188 RPM) and engine RPM (45 RPM). Those are meaningless.

Once it starts, the entire problem could be the faulty reading for the coolant temp. That's why we need a list of codes, and the data log. There is no code for the IAC valve in OBD-1.

Fatdog2

Sorry Injuneer.I should have re-read the post.Anyway BrentBrowning01's situation seemed close to this guy's issues(Zapper2003) on the LS1 site.
An update on the LT1 that was running bad
From 08-09-2010.Hope this helps.

brentbrowning01

Hey ya'll. I guess my problem was the Engine Temp Sensor (on the Water pump). I'm just guessing. I cut the wires and rewired it. Scan9495 isn't showing the Coolant temp at -40 anymore. I took it for a short drive to test to see if the engine would sputter and it didn't. Next thing I'm curious about is engine temp. During my ride, (probably 3 miles) my coolant temp in scan9495 got up to 202. My engine temp, according to my digital temp gauge read 232 by the time I made it home and parked in the garage. I turned both fans on via the scan9495 actuator module about a minute before I parked but soon thought that the fans wouldn't help the actual engine temp. What median engine temp should my car be?

brentbrowning01

DLOG-Save-2016Jun12-020016-2G1FP22P0S2111881.csv I mentioned earlier that I went for a drive.... While I was out driving I had my Scan9495 scanning. Yeah, well when I got back to my garage my computer decided it wanted to update to windows 10. So I lost the scan I was going to post. I went for another drive after my computer updated and this is what I got.
Before I uploaded this I made sure the columns were labeled. Hopefully this works..

GaryDoug

I have found that the Windows 10 upgrade is very slow at restoring all your files. It could take hours, so be patient. When I upgraded, all the folders and files on my desktop appeared to be gone and there were a lot of files in the recycle bin. The next morning everything was back to normal. There is a good chance the missing file is where it was before now.

brentbrowning01

All of my files were ok, GaryDoug... Did you see my scan?

GaryDoug

The scan looks ok to me (no expert). If anything, there might be a little slow response by the engine to a changing throttle. Might want to check fuel pressure on the road. I am not used to reading the data so what I saw was at 50 mph and that may be normal.

What kind of digital temp gauge do you have? I assume it uses the stock temp sensor in the head. Right now I would trust the new sensor (in the water pump) reading (pcm) to be correct. The scan tops off at about 225F and the low speed fans are normally programmed to come on at 226F.