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Thanks for the reply stilealive, in that case I'll throw it on tomorrow. I just came back inside from working on the and here's the latest. I bought a new connector for the oil pressure sensor and installed it. Got my battery charged back up while at NAPA. Cleaned and reinstalled the map sensor, very very carefully reinstalled the intake and cleaned the maf sensor with electrical cleaner. Fired it up and,,,,, still running like it was before. Even the oil pressure sensor is still broken. I don't know what I'm doing wrong but when you turn the ignition on the oil pressure gauge slams the max peg in the gauge without even starting.I'll see if there's any codes in it tomorrow. The scan tool I'm using is a blue driver scan tool. It won't let me change anything other than clear codes
Especially the ground inside the wire bundle coming directly out of the PCM. Next time you start the engine......grab that wire bundle and rock it back and forth....see if there's a change in how it runs. Try that before you swap the Crank Sensor.
Ground thats attached to the rear of the passengers side head too....check it.
You've changed so many things now it's hard to tell what the hell is going on, you've got to RELAX with "fixing" and replacing things that aren't broken. You've just introduced a whole slew of things that could be compounding or masking the real problem here. You have to measure things before you deem them good or bad.
For example you've replaced:
Fuel pump - did you verify the fuel pressure now at the rail? Maybe you kinked a hose, have a leaking fitting, new pump was bad, bad pump ground, ect.
MAP sensor - did you verify the connector to it is good? Does it have a good ground, 12v and output a normal looking signal voltage? You have a new one but again how do you know? It could be bad wiring harness to it, connectors, or it may be bad right out of the box.
Crank sensor - don't have a clue why you went here without some kind of reason, you would have popped a code here when the cam and crank readings didn't line up.
You've also pulled the intake a few times now, again introducing more potential issues as you've already found when you found a torn hose. Now you have to consider you could have torn another, pinched a gasket, forgot to tighten a fastener, or pulled a connector out of another sensor.
You need to stop and take inventory of what the symptoms are.
Does it smell rich? After it's tried to idle when you pull a plug does it smell of gas like the cylinder is washing down? Do you're O2's voltages show high or low? What is your pressure reading before starting? What is it at idle? Does your throttle show a % even when you're not touching it? If you have a temp gun is one of the exhaust primaries colder than the others?
You don't need to be worried about a broken intake spring until you answer these questions. If the spring was toast then the valve would not open, which would not allow fuel into the cylinder which would cause a misfire that you're saying you don't see. Or it would have jammed the valve open which would prevent compression, which you've checked, and again cause a misfire. Don't worry about your oil pressure sensor, it's not going to cause your car not to run and can be fixed after you have sorted out whatever is keeping it from running and making you bike all over Florida now.
You have to take account of what your problems/symptoms are and narrow them down from there, anything else is a waste of time and money.
1987firechicken, thanks for replying, It's good to here back from you, Last night I reconnected the battery before I went to bed and I'm going to leave it connected so that I can see what codes are in it. Thanks for letting me know about the oil pressure sensor, I thought with it acting up it would cause more problems or engine codes that's why I've been trying to fix it first. I didn't have fuel pressure tester in the beginning but I do now.When I tried to start it yesterday it has the same PSI since I installed the new pump a little over 50 while it's trying to run, and the pressure stays the same even after it stalls. After 24 hours without starting the gauge still shows 47 pounds.I think the fuel system is ok. The reason I replaced the MAP is because it threw a code for the MAP once so I cleared it and it came back. I bought a crank sensor because I was told by someone else that their vehicle did the same as mine and it ended up being the crank sensor. I did not put the new one in yet. I've been disconnecting the battery while working on it which clears out the codes The plan was to fix the oil pressure sensor first to try to eliminate any new problems that sensor could potentially cause. Get the battery checked and charged up then leave it connected to see what codes are still in there and deal with those. Then I was going to start live scanning and posting the results on this site. I can only data log 4 parameters at a time according to Blue Driver. After that I hope it's fixed because I'm all out of ideas. Thanks again for you help
1987firechicken, thanks for replying, It's good to here back from you, Last night I reconnected the battery before I went to bed and I'm going to leave it connected so that I can see what codes are in it. Thanks for letting me know about the oil pressure sensor, I thought with it acting up it would cause more problems or engine codes that's why I've been trying to fix it first. I didn't have fuel pressure tester in the beginning but I do now.When I tried to start it yesterday it has the same PSI since I installed the new pump a little over 50 while it's trying to run, and the pressure stays the same even after it stalls. After 24 hours without starting the gauge still shows 47 pounds.I think the fuel system is ok. The reason I replaced the MAP is because it threw a code for the MAP once so I cleared it and it came back. I bought a crank sensor because I was told by someone else that their vehicle did the same as mine and it ended up being the crank sensor. I did not put the new one in yet. I've been disconnecting the battery while working on it which clears out the codes The plan was to fix the oil pressure sensor first to try to eliminate any new problems that sensor could potentially cause. Get the battery checked and charged up then leave it connected to see what codes are still in there and deal with those. Then I was going to start live scanning and posting the results on this site. I can only data log 4 parameters at a time according to Blue Driver. After that I hope it's fixed because I'm all out of ideas. Thanks again for you help
Everything “1987firechicken” posted is good stuff....
But.....all of these PCMs in 98-02 Fbodys ARE NOT created equal. Some throw codes.....some don’t....some throw them early as a sensor is starting to fail but still works......some throw a code ONLY after a sensor has literally failed completely. Some PCMs are sensitive and throw codes very early at the first hint of a bad perimeter...these are the cars that will show different 10 codes for one simple problem. Then you go nuts figuring out which code it the correct I’ve and then you need a good person that can read a scanner to seek out the culprit.....those PCMs are called “The wife PCMs”...too much to say....lol
My PCM will NOT throw a code if I have a dying 02 sensor....while the engine is running like crap....only way to know something is wrong with them is having symptoms and scanning it to watch how they are switching with the engine running.
Crank Sensor: I get no code while engine is backfiring, sputtering and stalling out. Then bam....it runs perfect for a day. My car is sitting at home right now parked after two weeks of wierd backfiring and stalling episodes with also having it run perfectly fine in between and after every restart after it stalls. I finally got a Crank Sensor code that popped up after two weeks. I’ll change it as soon as I get home from being overseas.
Coolant Temp Sensor: Some of our cars can run perfectly with it unplugged or failed......my PCM will not allow my engine to run. If started with it unplugged or totally failed it spits raw fuel out the tail pipes, sputters, the throttle does nothing when pushed and then it stalls after 5-8 seconds of that. Plug it back in or replace it.....everything is perfect again.
TPS: No codes period for that one wearing out or failing.
So you cannot expect a code for every failure every time. These PCMs are friggin great in a lot of ways, but they are also just like the older 1970’s and 1980’s cars with .....IDIOT LIGHTS.....after something 100% fails.....you know it....and a light comes on to tell you what you already know.
Also....unfortunately our cars are getting really old. A lot of issues are not parts or sensors failing. It’s the wiring and connectors getting old, dry rotting and wires are getting exposed from wear and shorting out or arcing with water or touching something.
A complete new engine wiring harness on these cars would stop A LOT of peoples problems and daily little issues....but nobody really thinks to do that or wants to spend the money on it because it’s in the hundreds of dollars. But it’s a necessary upgrade for 20 year old cars.
Crank Sensor for you......it’s just another thing that causes your exact symptoms. Might not be the problem. But check your ground wires first.....and check that wire bundle to see if moving it around changes the way it runs. I had a broken PCM ground wire inside that bundle causing my engine to misfire terribly and/or not want to start sometimes. A wiring guru and tuner came to my house and said go turn the ignition to ON.....not start it......he looked at his scanner while rocking that wire bundle back and forth and he saw something on his scanner going on and off as he rocked the wire bundle. He says I’ll have you fixed up in 20 min. He cut the bundle open about 10 inches downstream of the PCM. Yanked out a red ground wire...cut it and spliced it back in with a different wire. Problem solved. Not saying this is your issue.....but these wires, plugs and other connections are old....and create problems.
Good thing about the Crank Sensor....it takes 15 minutes to change. If that doesn’t fix your problem you remove it....clean it up....return it for a refund. Just tell you never installed it because you found the connector to be bad so you just fixed the connector.
Thanks for the reply. My CEL system is the "late for the party" style lol!! A couple of years ago I replaced the coils plugs and wires and my car started running rough for about 2 months I chased the problem around thinking it was defective parts. And then one day the TCS and ABS just stopped working and the check engine light came on. I run the scan MAP sensor low voltage no signal. To make a long story short, when I was installing the new coils, I knocked the connector loose on the map sensor! I plugged back in, no codes running perfect!! It took almost 3 months for it to throw the right code! Well I'm heading outside to hopefully fix my car this time. I'll report back later. thanks again!
Looks like I gotta pull the intake again. The last time I got a map sensor code the TCS and ABS turned off, and MAP was unplugged. and that's exactly what's happening right now. Both of them are off right now
Please do not touch your crank sensor and introduce something else, I disagree with what @stilealive is telling you about how PCM's throw errors, they have code setting criteria and if you meet those conditions you have a CEL period, they are a computer and don't free-will "decide" to set codes or not. Yes, if you have an issue that is intermittent like a chewed up or broken wire that occasionally work it can reset failure counts in some CEL conditions, like O2's or a crank sensor.
YOU HAVE TO CHECK YOUR MAP .... FULL STOP!! It explains your issues exactly, and you have an active code for it, it has to be fixed no matter what.
"Code P0108 sets when the voltage to the PCM from the MAP/Baro Sensor Circuit stays above 4.5 volts for 10 seconds or more when the values from the Throttle Position, RPM and Oxygen sensors are changing."
That right there is what your PCM is seeing your MAP is STUCK above 4.5 volts on a 5 volt scale!!! That means the MAP is as I've already told you seeing wide open throttle pressures at idle, that is NOT normal and 100% is an issue. You also need to check TPS, you can do both with the scanner you have in your toolbox. Just log pressure and TSP position, that's it.
When you think you're good:
Config the scanner at key on and record the pressure and watch your TPS for a few seconds, they should both not move and your pressure should be at near 14.7 PSI or 100 kPa. Then start the car, again watch your readings, your pressure should fall off to the 50 kPa range and your throttle position should be again 0.
Please do not touch your crank sensor and introduce something else, I disagree with what @stilealive is telling you about how PCM's throw errors, they have code setting criteria and if you meet those conditions you have a CEL period, they are a computer and don't free-will "decide" to set codes or not. Yes, if you have an issue that is intermittent like a chewed up or broken wire that occasionally work it can reset failure counts in some CEL conditions, like O2's or a crank sensor.
YOU HAVE TO CHECK YOUR MAP .... FULL STOP!! It explains your issues exactly, and you have an active code for it, it has to be fixed no matter what.
"Code P0108 sets when the voltage to the PCM from the MAP/Baro Sensor Circuit stays above 4.5 volts for 10 seconds or more when the values from the Throttle Position, RPM and Oxygen sensors are changing."
That right there is what your PCM is seeing your MAP is STUCK above 4.5 volts on a 5 volt scale!!! That means the MAP is as I've already told you seeing wide open throttle pressures at idle, that is NOT normal and 100% is an issue. You also need to check TPS, you can do both with the scanner you have in your toolbox. Just log pressure and TSP position, that's it.
When you think you're good:
Config the scanner at key on and record the pressure and watch your TPS for a few seconds, they should both not move and your pressure should be at near 14.7 PSI or 100 kPa. Then start the car, again watch your readings, your pressure should fall off to the 50 kPa range and your throttle position should be again 0.
You're wrong. PCMs do not set SES codes the same. Some are very touchy and some totally suck at it.
I really couldn't care less if you think I'm wrong. I'm not here to debate you and your anecdotal evidence that you've somehow discovered AI in ECMs, you should probably call NASA or someone and tell them your PCM is self aware. Codes are set by criteria end of story, if those criteria are engineered properly and sensitive enough is debatable and I would entertain that argument, but not here.
The point of the thread is to help this guy fix his car so he can stop having to hoof it everywhere in the heat, I'm trying to help him and you want to argue, take it somewhere else. I've asked him to check out sensors that are showing a fault, nothing more, nothing less.
Hey everyone here's the latest. I managed to remove the defective map sensor and reinstall the new one without removing the intake manifold. I check the plug and had 5 volts going to it, and I'm pleased to announce that there is no longer a p0107 code in the system! As a matter of fact there are no codes in it right now! but now it will not stay running at all. my scanner has a setting called Freeze Frame, and here are the results from that Freeze Frame.
The picture with the 94 kpa was a screenshot I took while the car was not running, but the key was on. the TPS results on the screenshot, I noticed every once in awhile just for a second it would jump up to 0.4% would go right back to zero
Last edited by br549; 08-06-2020 at 09:21 PM.
Reason: update
Here's the live data scan I did tonight, It wouldn't stay running so this is all I got for this scan. I replaced the map sensor, and checked the voltage on the connector which was 5 volts. I cleared the code P0107 and re scanned, while scanning I noticed that the little round sensor in the air intake, the one closest to the air filter was not plugged in. The scan showed multiple codes but I'm pretty sure it was from that 1 sensor not being plugged in. I cleared it and scanned it again and thankfully there are no codes at all. Even though it is CEL free, it is defiantly running worse than it was before. It takes 2 to 3 attempts to start it and it won't stay running for long. What should I check next? Thanks in advance.
Last edited by br549; 08-07-2020 at 12:13 AM.
Reason: correction
I forgot to mention, Tonight when I was trying to start the car after replacing the MAP, You can definitely smell gas, after the car stalled is when I noticed it. I had the rear hatch open and both windows down.
I really couldn't care less if you think I'm wrong. I'm not here to debate you and your anecdotal evidence that you've somehow discovered AI in ECMs, you should probably call NASA or someone and tell them your PCM is self aware. Codes are set by criteria end of story, if those criteria are engineered properly and sensitive enough is debatable and I would entertain that argument, but not here.
The point of the thread is to help this guy fix his car so he can stop having to hoof it everywhere in the heat, I'm trying to help him and you want to argue, take it somewhere else. I've asked him to check out sensors that are showing a fault, nothing more, nothing less.
LOL
First....try not to be a total ********, half will do. We have enough of them in the world to deal with already.
Second, your ignorant to how these PCMs work. But thats ok, most people are. I used to be.
Third, all I said to the OP is that those symptoms are the same as a failing Crank Sensor. I told him clearly not to install it until he checks other items. Some PCMs will not throw codes at the same time as others. Start a thread and see how many people agree with me....and totally disagree with you.
Forth, Firechicken....you are correct, all anyone is trying to do is help. But you must look outside the box when it comes to codes and these PCMs....these PCMs LIE a lot....and miss things a LOT....and never tell us things a LOT. Don't just tell the guy to replace what the code says....there's more to it than that. So remove your head from inside your *** and bring it outside so you can see the big picture.
I forgot to mention, Tonight when I was trying to start the car after replacing the MAP, You can definitely smell gas, after the car stalled is when I noticed it. I had the rear hatch open and both windows down.
Huh....firechicken felt if you just replace the MAP you should be good.....LOL.....Yea.
You need to have someone scan it while the engine is running to find these wierd issues. Whenever the PCM fails to tell you which sensor is failing or failed......the codes that appear can be all wrong. These PCMs...as I've TRIED to explain DO NOT all function the same. I have friends with these 98-02 Fbods.....and some PCMs are rock solid, they tell all the first time every time. Most do not.
Get it scanned. OR....throw that Crank Sensor in.....see if it solves your issues. Its much easier than R&Ring the intake.
Like I said.....the last 2 weeks my engine has suddenly, while driving it, backfires, sputters and stalls. Probably twice a day. Each time I pulled over to the side of the road, turned the key off and back on......and bam it ran perfect again until the next backfire/sputter/stall episode.
NO CODES
NO STORED CODES
NO SES light
On day 13-14 it was just idling in the driveway. I was standing outside the car and bam....backfire/sputter,stall. BUT this time what do you know....SES LIGHT was on. I checked it.....Crank Sensor Low Performance.......CODE was there. Huh......."firechicken" how did that happen.....? All PCMs operate exactly the same.
08-05-2020, 02:59 PM
