I have a dry shot that sprays through the MAF. It worked great then I changed two parts since I last used it. The MAF and the bottle. The MAF is out of a 2003 Yukon, (my truck is an 01) and the bottle is a very used old style, skinny and longer, 10lbs NOS bottle. When I spray now the O2’s (narrow band) are all over the place, and I can hear audible detonation.

I tested the contents of the bottle in the chem lab at my university and its 99% pure nitrous, so I can eliminate a bad fill/contaminated bottle. That would tell me that its in the MAF not being the right one. However, it runs fine when off the nitrous so I would believe that its not the MAF. Only changing those two items why has my nitrous stopped working? Can anyone else think of anything to test?

(Just try this link, I cant get the pic to post)

 

Have you tried swapping back the original MAF and spray with the new bottle and vice versa?

*edit* Is that a picture you posted? It's not working on my side.

 

??? The pic was working a moment ago???

I dont have either of the old components to swap back and test. Your truck is a 2001 right? Why don’t drive up here and I can try you bottle/MAF and see if it helps

 

not working for me either....

k now it works

 

 

Heh, you're welcome to come down and try my MAF and bottle
I have no idea what's wrong so I'll just throw out ideas....
Have you tried just spraying the wet shot?
Try a fresh tank of gas?
What are you using to log? Can you post a screen shot?
What bothers me is that you say only changed those 2 things, but you checked both of them and they seem okay. Hmmm...maybe it has nothing to do with the 2, maybe it's a failing fuel pump or something? Do you have a fuel pressure gauge?
*edit* Try changing the fuel filter???

 

its 2 lean.

 

Thats kinda what Im thinking at this point. A diryt fuel filter would be the most likely.

I have no really way to test the MAF other then it works fine for normal driving and nothing looks odd on the scan tool. I dont have any data logs, and I dont want to go out to get some because of the audible detonation.

As gas has been getting closer to $5.oo a gallon I have been going into gas saving mode. And running what I call dirt gas (I always run a few tanks of good gas before using nitrous). Im thinking the dirt gas, which is more camel **** and alcohol then actual gasoline, has contaminated my fuel system. But I have ran the smallest jet I have to lessen the load on fuel system and test it and it still doesnt seam to make a difference on the way the nitrous works (or in this case doesnt work). Wouldnt a dirty filter be noticeable in daily driving?

Over the next week I will get a new stock replacement fuel filter, get a dry weight, change it, get a dry weight for the old one. Then cut it open to see the level of contaminations.

 

You're running the smallest jet on the dry shot correct? Have you tried disconnecting the dry shot and just using the wet shot to see if there's still any detonation?

What do you mean "get a dry weight" ?

 

I only installed the wet portion recently and have not used it because the dry isnt working and Im apprehensive to try the wet until I figure out the dry. At this point the wet is not wired.

Dry weight is just that. Dry weight of the filter, the old filter will have some gas left in it when I pull it out so I need to let it dry before I can get an accurate weight to compare.

 

Well, I would try the wet shot because at least you have the option of jetting it rich. If you spray a rich shot and get no detonation then that somewhat rules out a bad fuel system. If you still get detonation on the rich wet shot, then I would imagine you have fuel system problems. Like I said before, I'm new at the nitrous thing so I'm just throwing out ideas


I get ya
I must've had a brain fart when I read it the first time

 

Ive thought about that. The wet shot would eliminate the MAF variable also. Tomorrow I will be in the Chem lab, and get the weight of the replacement filter, to use as a base line for how dirty the current filter is. I have a felling that is the culprit.

 

The difference in weight should be interesting. Keep us updated please

 

Well I weighed the new clean filter today. I wont get a chance to change it until this week end. And, I wont get a chance to weigh the old one until next Tuesday. So I post more when I know it.

I went to the dealership to get a factory replacement to help eliminate any variables. It was close to $28.oo. And the filter weighs….

141.30g

 

I would say check the maf. May not be the same as your 01. This could lean out your tune on gas. You wouldn't notice it much if it was just a little lean. Then when you hit the N20 It could be going leaner and causing your spark knock.

First order of business is get a stock MAF back on. If that doesn't solve it I would look for other things.

 

GoldenVelvet, do you have a custom tune?

 

I no longer have the stock MAF to swap back. If Im not mistake the only thing that changes I different MAFs is the frequency calibration and the actual fuel map is on the PCM. If the frequency is off from what the PCM is wanting to see I would always be lean because the input signal is wrong. But its not just lean the O2's are erratic. If it was just the MAF calibration I would think with a very small I would be able to see it happening. However, I have ran the smallest jet I have and it did not make a difference. The problem was still there.

At this point Im thinking there is a problem in fuel delivery. Bad fuel? Dirty filter?

Chingon: I use stock tuning when running N2O

 

Where do you fill up? I only use 91 octane at 76 stations. A lot of them have banners up that say "No MTBE." I make sure to use those stations. Other 76's say that the gas may contain Ethanol.
Have you changed the fuel filter yet? If you can, get a fuel pressure gauge, I think it should be around 55-60psi.

 

Just giving you an update on the nitrous situation. I changed out the filter last Saturday and got a chance to put it on the scale on Tuesday. Now this is a scale that is so accurate that it can weigh a fingerprint, or a temperature change. Even still I was only worried about two or three places after the decimal not ten or eleven.

The gas that pourd out of the back side of the filter was kinda blackish. The dirty filter weighed almost 30 grams more then the clean one (!!!). The truck runs better now. I havnt gotten to play with the nitrous yet, but, Im convinced that was a big part of the problem.