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Hello everyone I think my map is going bad I'm new to diagnosing with hptuners but my truck has been surging and stalling at idle speed and this is what I see on my logger looks like my kpa goes to 100kpa without warning truck surges then goes back to idle comfort zone 40 or so then I give it some pedal the map will start reading normal for a short period then does it again about three key cycles later .https://www.dropbox.com/s/fpxf0oecye...14554.jpg?dl=0
Instead of posting a picture of the log, why not post the log itself? Would be alot more helpful to see more of the story and scroll around the issue to see how things are acting/reacting.Quote:
Originally Posted by Babyocho
In any event, from the looks of things, it doesn't appear to be a bad map sensor. It looks like the MAP signal is spiking due to throttle surge (when throttle ramps up suddenly, naturally MAP raises with it). So, I'd be looking into the cause for idle surge.
Thanks man I'll try that next time . I just used a screen shot because I'm away from my laptop but that makes a shit ton more sense to do though . I pulled the map and ran the truck for 5 minutes without touching the pedal and it did it uninterrupted no stumble no stall all it did was adjust timing and tps to deal with the constant 110 on map input and backfired like crazy when revving.
Post a log and your tune. That's the only way anyone is going to be able to really help. Along with a log of the vehicle running that demonstrate the issues you're having, get a log of "Key On Engine Off" so we can do a MAP sensor rationality check.Quote:
Originally Posted by Babyocho
this is the only log i have at the moment that shows both normal idle and the surge its from the screen shot i posted earlier
Your MAP sensor is working fine. The reason you see the MAP signal spike is because of the surge at idle. The throttle opens in an attempt to save the engine from a stall condition, which means a sudden influx of aircharge, causing the intake manifold pressure to rise (equalize with atmospheric pressure). You can also see the spark working in conjunction with the TB trying to save from a stall condition. But, as you can see just prior to the surge, your timing is in the negative at -6*, and that also during this time, you're in open loop. Once the PCM enters closed loop, it is trimming 15% fuel in order to achieve stoich, and after it has done this, timing settles into a -5/+5* oscillation as it uses spark to help stabilize the idle.
The fact that your spark is -6* prior to entering closed loop, and the fact that the fuel trims pull 15% after closed loop, this tells me your fueling is obviously rich and needs some work. A rich AFR will cause an elevated idle (until it gets so rich that it starts bogging), and as a result, spark is trying to pull idle down to target RPM during open loop by using negative advance. Between negative timing and fueling needing to be dialed in better, these are things that will certainly cause an unstable idle condition.
What are the details on the modifications to this vehicle? And when you have a minute, post the tune file so we can have a closer look at what's going on.
here is my tune it's just a stock one for the most part accept modded for the cat delete at the moment. As, for mods i have a cold air intake, 180 tstat, e-fan, cat-delete. during both of these test though intake was pulled off to visually inspect for blockage
this is happening after a timing job and head gaskets i could have sworn i had it timed down to a T but its possible its a botched job.
I'm gonna recheck timing put back on the intake and try firing it up maybe it's the iat reacting to atomspheric pressure
Why have you disabled nearly every single diagnostics check in the tune? Having all that disabled will sure make tracking down any issue a lot harder. You should really only disable a certain few items in order to avoid nuisance codes for modifications that you know ahead of time will cause a code that doesn't need to be worried about.
If you did botch the timing job, the PCM would probably recognize and relay that information to you via the On Board Diagnostics, and you'd likely see code P0016. But, since you have that code disabled in the tune, it will never tell you.
Hell, you could have a myriad of things wrong (connectors not fully seated causing a bad connection to any number of sensors), and you'd never receive a CEL and accompanying code for it since everything is disabled. You've crippled the on board diagnostics of the PCM. Bad move.
Just not using my common sense to be honest . That's where I'll start first then.
Such a noob mistake man . I turned them back on accept most 02 codes and the truck started running a whole lot better my dtc came back with a bad map code right away though nothing else yet got a log of the truck running pretty good even on the bad map untill I added a touch of throttle and it back fired and stalled and smelled like gas which Is probably because it's flooded from the map reading so high right or am I reaching here ?
And I only know it's really bad this time because I plugged it back in and it stopped fluctuating period which is the new log test I did today
here it is with the corrections
So, you're saying that this log was done with the MAP sensor plugged in?Quote:
Originally Posted by Babyocho
Why don't you go into the scanner diagnostics and special functions, and clear any and all DTC's, and reset all adaptives. Then, cycle the key off and back on, fire it up, see what codes return. Post the codes that pop up.
Yes this is with the map plugged back in it must have went bad between that day and when I tested and unplugged it to do the second test . The map was pretty nasty inside when inspected and I also had the same code when my truck died originally because of a blown head. I did also notice that the stft when the map was working was at a negative and would zero out as it raised in rpms then readjusted to a negative then when the map went out it was super rich and when I tried throttle the tps went no where and stft went to about 20 percent and the truck died all together which makes me think a shit ton of fuel and no air was the cause along with the map causing the already rich scenario
Alright I'll try right now before I leave work
so this is the second attempt with the steps you told me same code popped up just ran for a shorter period of time
it was P0108
OK, so possibly bad MAP sensor, or you have a short in the circuit somewhere. Would be a good idea to do a continuity test between the MAP pigtail and the PCM connector. Just be careful when probing the PCM connector pins as you can damage them if you're too forceful.
Alright I'll check it tomorrow with my tester thanks !