Stuck at 120 Mph

[sprucegagt]

I know, I only did it once for about 35 seconds. I just baught the DHP tuner. Ill tune with out the MAF with 36# injectors, and see how it does. After that I will decide to throw the MAF back in the mix. "I really tring to avoid that if posible. Hey I got to 120 really quik though."

bwahahahahahah.....bwahahahahaha.... okay let me catch my breath.

One question, what MAP sensor are you going to use?

[john_V63400]

How do i get a 2 bar map , And would it be diffucult to throw in my MAF.

Do I just buy a Stock MAF from the dealer and hook it back up pr what. Cause I really want some hope please.....

[tejohnson]

You can buy a 2 -or- 3 bar map from Pace Performance, GMPD, Summit Racing, Jegs, etc.

Don't you have your old MAF? Otherwise, go to a junkyard and find one. Heck, you can even hack in an LS6 MAF. It has a built in IAT sensor, so it makes the plumbing easy if you have an IC.

[john_V63400]

Ok thanks, I baught my car with the supercharger on it. So I dont have the old one.

[AaronGTR]

holy cow, yeah that's probably why they popped. It's bad enough to go lean when NA, but you have boost, and going lean = detonation time!! Wow yeah I'd say that's what did it.

I know it feels funny. It doesn't shut off the fuel totally, so it doesn't just stop running, and the RPMS don't go down as it's just cutting the fuel to the injectors like 1/2 the time. So it's like a soft RPM limiter, only instead of limiting spark, it limits fuel. It's bad to hit that. ESPECIALLY on a boosted motor!!

Actually the grand am speed limiter doesn't work like that. SE's are limited to 105 and GT's to 126. When the governed speed is reach it shuts off all fuel for a few seconds so the rpm drops and you lose speed until it turns the fuel back on at 123mph and you start accelerating again. It'll just keep bouncing back and forth like that 3-4mph. I did it plenty of times in my car before I had the governor removed. Never held it there though. There is also an ignition limiter that will enrich the AFR and retard timing to limit top speed. It's set at 130mph in every gear in the stock program though, and since you'll only see 130 in fourth you can modify that speed limiter in fourth gear and effectively remove that limiter. Only reason I can think why he'd only hit 120mph is too much drag/not enough power, or just because the engine and tranny are in "limp" mode all the time from having no MAF and no proper tune.


Like everyone else has already told you, first step is get a maf and get a tuner! Until then you should even be driving that thing.

[kflo 93 gt]

It does have that big body kit on it. I'm sure that's not helping the cars drag coefficient any.

[IsaacHayes]

The computer is designed for a MAF, no getting around it. It's like disabling the camshaft sensor and saying well if the old 3.1 cars can get around w/o one then mine can... It wasn't designed to run without it. Sure you can remove it and it runs, but not optimally.

Part of tuning and going fast is designing the system to run well. Anyone can throw a power adder on, but the ones that go really fast and make good reliable power are the ones who tune.

Put the MAF in AFTER the BOV. You might have to go with all new charge piping, and route it away from the SC and TB, put the BOV, then MAF, then route back to the TB. Heck if I were you I would take the time to buy an intercooler that would fit, and route the setup through all that. That would give you more power and less chance of knocking. Then I'd drive it a little and scan for KR and tune in areas that need it carefully. Probably remove some timing in the upper RPM's, etc. adjust fuelign if needed...

Did you rebuild the engine yourself? You don't sound very "confident" or knowledgable about some stuff (no offense). At least get the MAF in there, you can figure it out. Make sure it's after the BOV.

One thing at a time. I know it's hard to stay off the throttle, but just because the motor is in and running doesn't mean it's ready to go play yet.

[john_V63400]

Yeah I completely agree with you isacc. I dont know didily about engines, but Im learning. Im only 19 so bear with me. Im going to put in that MAF asap. Once as I see what one looks like I start planing the setup, but I am putting in a intercooler. I misewell sence Im throwing in the MAF in the mix, Anyways hopefully it will start running better after the MAF. But serius, will a 2 bar map be easier than installing the MAF back in or what.

[tejohnson]

Although the 2 bar map could be added in without adding the MAF, you still should put the MAF back in. The 2-bar will require quite a bit of tuning since you will need to scale the map in the calibration.

The reason I mentioned it in the first place is that it is better than nothing at all, and your PCM will have some clue of how much air is being pumped in. I was never under the impression that installing a MAF was very hard tho.

[john_V63400]

yeah, agreed. Im installing MAF ASAP. I guess weve learned RSM sucks, driving without a MAF is very bad and has no performance. Ok bye

[IsaacHayes]

MAF will be easy, you just put it in line with the charge pipe right after the BOV. You might have to shorten/lengthen the pipe or add another coupler or something, but that's it. Then just connect the wire back to it and go.

[95SleeperAcheiva]

" I'm only 19 so bear with me." Don't ever let age speak for you. Especially with cars. I was 8 when I had a conversation with Newman on cam profiles. I had my master certificate at 16. I was reading, writing, basic math and fractions at 5. Justr so I could work on cars with dad. I should have been working at a dealer at 16 making $25 an hour and they wouldn't hire me because of my age. I've learned a thing or 2 from younger mechanics. No excuses. Learn it. Research it till you can build it from scratch, then build it.

[john_V63400]

Well your kinda right, but what I was really trying to say is I just started to work on engines this past year. But I get you point.

[SappySE107]

I started skimming a few posts up so hopefully im not repeating. Put the stock MAF in andstart with a stock code. You will have to up the fuel most likely at the higher flow readings. Forget the 2 bar map unless its needed for a trans setting or something. Im not sure what all is used on a MAF setup for the MAP input so check into that.

[IsaacHayes]

Ben, the RSM is runing stock code as far as tuning from what I've heard. The FMU is the only thing dealing with boost/fueling.