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ok so done alot of tests since the last time I posted, My AFR guage works, I tested it, I bought a New MAF took screen out and put it back in, (My car was tuned with screenless MAF though ) not the problem because the air/fuel ratio is still bouncing alot during driving whereas before it would not, that much, like cruising from 13.5 to 15.3 back to 14.6 briefly to 16.0 cruzing. On the guage and when I go WOT in boost it doesnt want to stay at 11.4-11.5 wants to come up to 12.5 then 13.2, as my previous post stated.
I have a new ac delco map sensor on the fast 102 I put some blk gasket maker around it to seal it, because they can be prone to leak.
I checked pvc hoses, I double checked header trq and collector, everything is tight,
This really has me stumped and could use some advice or suggestions. Thanks
Last edited by corvet786c; Sep 17, 2021 at 03:45 PM.
I realize that steve, but my car was running good tuned by the same person, I am not sure where to look for this lean condition, I have hp scanner everything looks fine. Thought you guys could give me mechanical advice to check on something I missed to fix this Thanks Chris
If you do not understand how things work, or how to fix them etc etc...how can you expect to diagnose and fix them ? Changing random parts is never a route to fixing something.
the best and safest advice to prevent you destroying the engine has already been given.
If you do not understand how things work, or how to fix them etc etc...how can you expect to diagnose and fix them ? Changing random parts is never a route to fixing something.
the best and safest advice to prevent you destroying the engine has already been given.
The parts that were mentioned earlier got the car running again, because it was broke down, again as I mentioned in that part, the car would start but not stay started, so I took it to a shop, They put delco maf and map, now car is running and drives fine, but not under boost. Thanks Chris
We used the same parts 1 Bar Map and new delco MAF, why is car running lean with same parts?
Last edited by corvet786c; Sep 17, 2021 at 04:30 PM.
The parts that were mentioned earlier got the car running again, because it was broke down, again as I mentioned in that part, the car would start but not stay started, so I took it to a shop, They put delco maf and map, now car is running and drives fine, but not under boost. Thanks Chris
We used the same parts 1 Bar Map and new delco MAF, why is car running lean with same parts?
My crystal ball is not working just at the minute....which is why you need a competent person who can actually check things on the car, with the car present to them.
You might fit parts, and it might run....but if it is not 100% right...you will damage ****.
I went WOT and the car just shut down, would start but not idle, it would cut off, So they diagnosed it as a bad MAF and a bad MAP, saying I need a 3 bar., Also I put new O2's in it, fuel pressure good, just got back from a drive.
So when I hit it the AFR Guage goes to 10.0 then rises to about 13.0 at about 4800 rpms and I just shut it down, Dont know what else to do anymore.
My question is just changing MAP, MAF or O2 sensors affect the tune if they were the same part number? I didnt think it would?
need to get the car looked at closely with hp tuners, and check things like injector, fuel pumps, filters, anything that could affect the base tune
the MAF and MAP are very unlikely to "fail" at the same time so finding out why the car shut down in the first place is very important to finding out why it doesn't run right now
did it set any codes? PCM could have some issues or something that caused the car to shut down. That needs to be determined and I'll bet a doughnut that it's not the map and maf going out
time to go back to basics. Is the engine healthy? good compression and even? are the new sensors good ones?? MAF and MAP are two very critical inputs so if they are bad sensors, (brand new or not, calibration can be off) the tune will react very differently
time to get with a buddy with a similar configuration so you can switch in some "known good parts" and try thinks out. Wouldn't be the first time a new MAF was way off. In the old days with turbo buicks you couldn't find good ones, hence the MAF translator which allowed LS1 MAF
root cause diagnosis is tough, but there is no substitute when reaching for the fix
sounds like a 3 bar sensor was stuck in there at some point with a 1 bar tune.
As mentioned, that won't work. Your tuner might be stumped too which is why another pair of fresh eyes (like another dr) is sometimes a good idea
I'm very "worked up" when my cars don't run right so I feel your pain. Time to be methodical. The car ran right and then something failed to make it shut down.
My car is in full "gremlin" mode and goes into limp home randomly. So I'm taking my own advice, going back to the service manual, and stepping through all the checks.
When all that good advice fails, I seek out my neighbor who is a 40 year ASE pro and he can read between the lines and based on many years of experience, diagnose problems WAY quicker than I can
suck squeeze bank blow give the engine what it wants and needs and it will do likewise for you. It will fix.
[QUOTE=corvet786c;1603987027]
Thank you for the input but alot of the issues you are talking about have been resolved, The old map and maf were toast. We put new delco parts in. My tune is off a 1 bar setup. I just need to find out what is causing to run lean. I also just bought hp tuners. The AFR guage seems to be more jump than it was before. What about a cracked spark plug, would that affect lean condition?
ok here is the original map sensor with the tune, Its a 1 Bar car was tuned for 1 bar, No DTC's I went to put the old MAF and car was running bad, so I put the new one on and its better.
This is a picture of my original Map
Last edited by corvet786c; Sep 17, 2021 at 07:32 PM.
Thank you for the input but alot of the issues you are talking about have been resolved, The old map and maf were toast. We put new delco parts in. My tune is off a 1 bar setup. I just need to find out what is causing to run lean. I also just bought hp tuners. The AFR guage seems to be more jump than it was before. What about a cracked spark plug, would that affect lean condition?
ok here is the original map sensor with the tune, Its a 1 Bar car was tuned for 1 bar, No DTC's I went to put the old MAF and car was running bad, so I put the new one on and its better.
This is a picture of my original Map
If you bought hp tuners then I wouks scan the car and post the scan, but dobt fo too crazy in WOT. The map sensor when going from 1 to 2 bar or 3 bar have different map characteristics that need to be changed in the tune.. But, if you removed the intake and then these issues started I would look for vacuum leaks,, even though you torqued it down you could have a flattened gasket...You never know....If you arexzying around with map sensors and have a SC I would consider removing the naf and going straight to SD...
If you bought hp tuners then I wouks scan the car and post the scan, but dobt fo too crazy in WOT. The map sensor when going from 1 to 2 bar or 3 bar have different map characteristics that need to be changed in the tune.. But, if you removed the intake and then these issues started I would look for vacuum leaks,, even though you torqued it down you could have a flattened gasket...You never know....If you arexzying around with map sensors and have a SC I would consider removing the naf and going straight to SD...
OK Thank you, and do you think a flattened Fast 102 gasket could cause a lean condition under boost because I have been reusing them for a while now?
Its worth a shot looking for a leak. But you said it runs smooth outside of going lean up top so it may be a long shot. But worth taking a peak....just have to look at the last things you did before the issue started...
Where is the wideband sensor? Any chance it's loose or anything like that? Is the car knocking at all when the wideband reports lean? How were both your maf and map "toast " at the same time?
Last edited by tabbruzz; Sep 17, 2021 at 09:51 PM.
Its worth a shot looking for a leak. But you said it runs smooth outside of going lean up top so it may be a long shot. But worth taking a peak....just have to look at the last things you did before the issue started...
OK thank you tabbruzz, the last thing I did was add techron to the tank and it sat for a couple of days, took the car out went WOT, and it shut off, The car would start but not stay started. Tokk it to a mechanic New MAF, NEW 1 Bar Map, Right now cars runs good like it supposed to. I am really starting to wonder if The FAST 102 Gaskets cant hold the boost about 10lbs, Because everytime I go WOT it starts out 10.5 AFR jumps to 11.5 around 4000 rpms then Immediatly 13.0 after that.
I have reused and torqued those gaskets a few times so I am going to reorder some. We shall see Thanks for your input, This helps.
Where is the wideband sensor? Any chance it's loose or anything like that? Is the car knocking at all when the wideband reports lean? How were both your maf and map "toast " at the same time?
Wideband is on the driverside, about 6 inches away from the collector and those bolts are tight with a gasket. Since I am using a stock1 bar there is a strap inside that stretches and measures pressure each and everytime past 14.6 psi, To my understanding, well keeping this up, once that strap stretches to much it breaks and the Map is no good. Yes Ideally I should of been tuned for a 2 bar, but wasnt. This morning I put the old MAF on and forget it, car was stumpling.
My specific tune is going to be related to the MAF readings, fuel etc.
I also reused the exhaust manifold gasket on that side....that the wideband is on
No I have not noticed the car knocking when lean. Thank Chris.
Last edited by corvet786c; Sep 17, 2021 at 10:08 PM.
I don't see it in these posts unless I missed it, but what about your injectors? What size? Is it possible that when you reinstalled the fast intake one injector or so is having issues? What fuel pump? Just throwing out ideas while I sit on my *** bored on a saturday....lol
I don't see it in these posts unless I missed it, but what about your injectors? What size? Is it possible that when you reinstalled the fast intake one injector or so is having issues? What fuel pump? Just throwing out ideas while I sit on my *** bored on a saturday....lol
Thanks Tabbruzz, those are good ideas, I checked those yesterday 86lb inj, and they are tuned for it, They look ok,
But the more I think of it the more I am suspecting the Fast 102 runner gaskets. Also when I got the car back from the mechanic My engine temps were 235 degrees further weakening the intake gaskets more, When I had put them on before taking car to mechanic they were soft and did not want to be put in place, so they would always come out of the rectangular position.
I also looked at the date because I save the box when I order parts and it was 2017 since I had them. But we shall see next week when I get a chance to install them.
You helped me out alot to narrow this down, Thank you for not critizing this thread but being helpful.
And if this doesnt work I will change out exhaust manifold, the side the Wideband is on. Thanks Chris
Thanks Tabbruzz, those are good ideas, I checked those yesterday 86lb inj, and they are tuned for it, They look ok,
But the more I think of it the more I am suspecting the Fast 102 runner gaskets. Also when I got the car back from the mechanic My engine temps were 235 degrees further weakening the intake gaskets more, When I had put them on before taking car to mechanic they were soft and did not want to be put in place, so they would always come out of the rectangular position.
I also looked at the date because I save the box when I order parts and it was 2017 since I had them. But we shall see next week when I get a chance to install them.
You helped me out alot to narrow this down, Thank you for not critizing this thread but being helpful.
And if this doesnt work I will change out exhaust manifold, the side the Wideband is on. Thanks Chris
cool...good luck...these problems can be a PITA sonetimes
Its those FAST intakes, I went ahead and removed it and put new fel pro runner gaskets on, cleaned everything. The old gaskets on the driver side had oil where it meets to the head on the bottom part, looks like that was where it was leaking, Buttoned everything back up, took a spin warmed it up and hit it a few times, AFR was reading 12.2 and holding. It was better a whole point, so I am happy with that, I went ahead and epoxied the MAP sensor to the intake, upper surface. I think when its sealed it should reach again to 11.5-11.6 where I was before.
The MAF and MAP seem to be doing their jobs so far.
