br549

Hey everyone hows it going, the other day I was driving down the road and my car just died. It would start right back up, but would not stay running. I thought it was the fuel pump, so I ordered an ac delco pump and when it arrived I installed it. Now it does the same as before, it will fire right up but then immediately start chugging at a very low rpm till it eventually dies. It will start right back up every time but then it will chug along for about 2 minutes before it dies again. If you touch the gas pedal while it's chugging it will die instantly. I tried to bypass the relay, #30 and #87 pin with a piece of wire and will not run at all with the jumper. I also replaced the fuel filter as well but still does the same. I'm covered with gas and a little frustrated right now but if anyone has any pointers or ideas they could spare I would greatly appreciate it. Thanks in advance. Also I scanned it it threw a p0108 and a co236 code

br549

Well I scanned my car again to see if any codes had returned, they did, and they brought friends this time. Is it possible that the codes that I currently have in my car, are capable of making it not stay running? I can't even drive it, It starts right up every time back to back, but then it will chug at about 400 RPM for a good 2 minutes before it dies, and if you touch the gas pedal while it's running it will die immediately. I'm gonna crawl back under the hood


and hope that the MAP sensor is just unplugged again! If I manage to fix this issue, I'll post everything I did so hopefully it help someone else on here.

stilealive

Two things cause those symptoms in my experience with my car for 22 years....

Failing Coolant Temp Sensor......makes my 1998 Trans Am run exactly as you describe after starting it and then it stalls. .It also sometimes will make the temp needle appear to move into the hot zone, back down, maybe jump around a little....... but your really not overheating. And sometimes the temp needle is not affected.

Or

A failing Crankshaft Position Sensor .......

Tyler Dietzenbach

iTrader: (5)

I vote map sensor for sure.

Tyler Dietzenbach

iTrader: (5)

Buy a new one and install it. They're cheap. Then report back.

I'll also add that it could be what the poster said above. Also possible its a vacuum leak.. It could also be MAF (not map) related. You could unplug the MAF and see how it runs that way first.

Your car is doing this, because the air/fuel ratio is way off.

br549

Well I replaced the map sensor and the oil pressure sensor, intake gaskets, fuel filter, the fuel pump, the entire PCV system, gave the intake a dawn dish washing bath. Almost forgot, The fuel pressure is 57 pounds while trying to stay running and held 47 pounds for 25 hours. The compression on all 8 cylinders is 125 pounds. put everything back in, and realized I ripped the wire out of the oil pressure sensor!! Scanned again, cleared codes, scanned again and now it has a code p0102 and p0108, and a c0240. So i'll be removing the intake again this afternoon when the outside temperature doesn't have 3 digits in it. I'm going to pick up a mass air flow sensor and a coolant sensor, and a crankshaft sensor today and throw them into to pit as well. I hope this works, this is my only vehicle and it's been broke down for about a month now. Triple digit temps +, bicycles, and 44 years old,= Sucks. Thank you for your replies, I really appreciate it.

Tyler Dietzenbach

iTrader: (5)

You can just unplug the MAF and if it runs you know its that. Better than just throwing parts at it.

br549

I unplugged the maf and it there was no changes. I'm gonna try cleaning it first because of the price of a new one

Tyler Dietzenbach

iTrader: (5)

Got it. Very unlikely it's that then

stilealive

Biut I think it depends when you unplug it.....if you unplug it immediately after start up cold....it should give you a change. But after the coolant passes 122*F the 02 sensors take over so if you unplug it then it should not have a change....

Can't quite remember.....all these damn electronics.....lol

br549

On a more positive note, I'm glad I pulled the intake off because I found an enormous vacuum leak on the PCV line in the back near the firewall. It was basically ripped in half at the rubber offset tee on the line. If I can get this current issue panned out, it should run better than it ever has since I bought it!!!

br549

When I unplugged it the car was cold, and I just reconnected the battery right before starting it.

br549

Last night out of desperation, I was trying to keep it running a little bit longer to try to collect some live data, I removed the air filter and sprayed oreily brake parts cleaner directly into the air filter box towards the throttle body and all that did was make it stall out faster.

br549

I was gonna post my live data scan from last night, but it won't let transfer the image to my pictures. I'll to translate. During live data scan my car ran for a total of 112 seconds. It was logging Intake manifold pressure, timing advance, calculated engine load, mass air flow rate (lb/ min),absolute throttle position. IMP was 14.6 until 102 seconds later it dropped to 12.4 then climbed back to 14.3 over 10 seconds. Timing advance 0 from start to 100 seconds. At 103 seconds it jumped to 17.2 then 18. MAF rate, 0 till 100 seconds then went to 1.7 for the last 10 seconds. Throttle position, 0 til the last reading at 111 seconds it went to 6.6. Those were the only parameters I had I had scanning at the time. I don't know if any of this info matters or not, but here it is

1987firechicken

Ugh some misdiagnoses here going on. You HAVE to square away your MAP sensor before anything else, that is what is showing a code and 1000% is highly involved in nearly ALL your fueling calculations. It makes sense if you have a pressure problem or a crazy MAP sensor it's pouring fuel into the thing thinking your flooring it or it's completely choked out. Maybe you got water in it during the cleaning?

You could have a high pressure readings in your MAP due to a large vacuum leak or your MAP is dead and giving false readings first and foremost. I'm much more familiar with measuring in kPA but after some conversions if what you are saying is you read 14.6 PSI at idle then you are basically sitting at atmospheric pressure at idle which is crazy. Looking at that you either have a MASSIVE vac leak, or your car naturally idles at wide open throttle. There are other things that can effect pressure readings but we'll start here first.

Alot here is not making sense either with what you described in your log and you'll have to provide a better explanation as well for us to help. Mostly what were the conditions of your log (idling entirely, did you rev, touch anything at all during the scan)?

Are you also saying that your MAF was dead until over a minute in and your throttle position changed without you touching it after 2 minutes???

Ideally you should check the MAP first since that is raising a code. Do you have a vacuum gauge you can use or borrow so you can verify what your MAP is displaying? You should be at about 50 kPA on your pressure at idle and a vac gauge should read somewhere just below 20, or if you have a smoke machine that would shortcut it real fast.

Unplug the MAF for now since it's not a requirement (it is involved in all fueling as well not just warmup and WOT like stated earlier) tackle one thing at a time. Firing the parts cannon at it is going to make you poorer and make things worse as now your introducing more things that have been changed and now could be a problem.

If you don't find something obvious scan for manifold pressure in kPA, timing (not just advance), coolant temp, RPM, O2 voltages, throttle position, and go from there. Also wouldn't hurt to pull out a sparkplug and see if it's covered in gas or anything else unusual that can lead you to something else.

br549

Thank you for your reply, I just came back in from removing the intake again. The single wire got ripped out of the oil sensor plug when I reinstalled the intake the other day. The pin is too small for me to repair, so I will pedal back up to oreilys in the morning and get another one. This has been quiet the journey, As far as those scanner readings go, The only thing I really understand about those numbers is what other, smarter people tell me. But I misdiagnosed the issue all by myself, it looked, smelled, sounded, even tasted like the fuel pump failed, so I Immediately ordered one, It took a week to get here, I had everything laid out ready pull the dead one, install the new one, had the rivet gun loaded and ready with my patch panel and sealer laid out like I new what I was doing lol!! I honestly thought I would rolling down the highway in about 30 minutes, I misdiagnosed that too!

br549

While I was back there, again I pulled the map and there was a little wetness inside the part of the intake it plugs into. I sprayed the map with electrical parts cleaner and wrapped it in a shop towel. I'll hit it again with the electric spray before I head out. You mentioned a vacuum leak, yes it definitely had a vacuum leak on the backside of the intake the lines for the PCV system, where the rubber offset tee sits was ripped completely into! I replaced the entire system while I was in there with a brand new OEM one. When I performed the scan that 100% idling, if I touch the throttle it will stall out. The scanner I'm using is a Blue driver scan tool, and it tells you not to scan more the 4 parameters at a time. When I get it reassembled tomorrow I will set it to metric readings and scan it for everything you requested and post it here. For some reason I can't transfer the live data files to my control panel on this site, they are csv or cvs files. I'll gladly type it all in or anything else you want to see. Thank you all for taking the time to help me out with this issue. Oh I forgot, the map sensor is brand new, purchased and installed 2 days ago.

br549

The spark plugs are AC Delco iridium, about 3 weeks old, I inspected them when I did the compression test, 125 pounds on all 8 cylinders. I didn't see anything out of the ordinary. Is there any way possible for something like a broken valve spring to not show up on a compression test? The reason i'm asking is, of all the youtube videos I have searched over the past few weeks looking for similar issues, there is one video that matches my issue the most. I don't know if I can say their name on here but they are the "2nd letter of the alphabet" and the 19th letter of the alphabet, customs. They went through some of the same diagnostic issues that I'm having. The T/A they were working on was starting and idling and stalling the exact same way that my car is currently running. The solution for their issue ended up being to replace a broken valve spring. I wouldn't think a broken valve spring could not hide from a compression test, but I've been wrong before. Update, my car has never thrown a misfire code or backfired.

br549

I got lucky while ago. I purchased a new crank shaft position sensor yesterday to throw on this morning, when I pulled the new one out of the box there's was a piece of paper in there as well. For some reason I decided to read it. In very small writing it states that you must have some kind of relearn scanner tool to make it work!! If I would have plugged that sensor in at this point in time, I would never figure out what is wrong with my car!! I have melted the barrel down on the parts cannon already! so now I'm waiting for my oil sensor plug to arrive at NAPA. And also the people across the street gave me a ride this morning so I decided to take advantage of the situation and yank out the Optima yellow top and get it tested, just to make sure. they said the battery is good but is low on voltage. right now they're charging my battery back up. Once I get back and get these parts installed i'll come back here and give an update

stilealive

Almost always no relearn process is needed. I've replaced Crank Sensors several times....you start it and drive it. If you want to you can disconnect the power for 30 minutes and the PCM is reset. It'll be fine.

I also did it once and the tuner who was doing it tried it several times and it would not complete the relearn. I said screw it.....and drove away. The car was fine for the next 10 years.

You need a real OBDII scanner:

Open the scanner, pick displays, VCM controls:

CASE Learn: To use the CASE learn function please follow these steps:

1. Put the vehicle into park (auto) or neutral (manual).
2. Turn off all accessories and A/C.
3. Apply the parking brake.
4. Press the brake pedal. Keep the brake pedal depressed during the entire procedure.
5. Press Begin.
6. Gradually rev the vehicle to fuel cutoff (around 4000-5000 RPM's) over a period of about 4 seconds. When fuel cuts out, immediately release the throttle.
7. Allow the engine to come back to an idle.
8. Turn the ignition off for at least 15 seconds. This step is required for the VCM to store the newly learned configuration.