I have ran 2 bottles through my car on a 125 shot with no problem. I recently switched my jets out for a 150 using a .063 Nitrous jet and a .034 fuel jet. I have a racetronix pump,pull 4* of timing, and run my bottle pressure at 950 psi if youre wondering. So anyway I make a motor pass, its a very hot and humid Louisiana night and I run a good all motor time and am happy with it so I decide to spray on the next pass. Well I leave on the botte and everything feels great but at the top of 3rd gear the car started poping, I thought it was a backfire so I hit the clutch and try to rev the motor to see if it still running, its still running but my throttle is dead. About 2 seconds later I hit the gas and its back. I got back to the pit and pulled the air cleaner and everything is as it should be, the car idles normal and restarts fine. So I thought maybe my revlimiter came in so I open HP tuners look at it and its @ 6800 where I set it. My friend suggests moving it up to 7200 so I do, and I pull my jets to make sure I have the right sizes in and I do.

I make another pass and this time does the same thing as soon as I hit 4th gear. I had been data loging so I looked at both of them, the first pass I got about 4* of knock and then notice after I let off and the pedal was dead that the TPS was spiking where I hit the throttle 3 times and so was the injector duty cycle but the RPMs were steadily decreasing. The second pass
log showed the same thing but not a bit of knock retard or burst knock at all.

I havent pulled the plugs yet (had to work) but I wanted to go ahead and post this up and see if anyone's ever had something like this happen to them. Thanks.

Hummer.

 

Need to check the plugs. What are they gaped at and how old are the wires?

 

Mine did similar when I did not have my plugs gapped right - especially when I upped the juice.

 

Tr-6's gapped @ .036, the wires are probably a year old, replaced them when I put the kit on the car, I was trying to do it the right way. I described the plugs to a friend and he thinks it went lean. The thread ring/base was black but the porcelan was almost white, the electrode wasnt rounded off but the ground strap had 2 marks on it. Te first mark was in the bend/curve and the second was closer to the base of plug. He said the mark closer to the base indicated a lean condition.

I want your opinion though, I dont want to rule anything out.
Almost forgot, my duty cycle was @ 97 % when it happened.

Thanks

Hummer

 

Thank you also. Do you think the flame front was blowing out the spark?

 

The more juice you use the more prone it is to blowing out the spark. Thats why the smaller gap. From your description it does sound as though you are going lean. Do you have a wideband or maybe a friend that can let you borrow one?

 

Yes I have an LM1, it read 19.XX and I freaked out when it happened but
a friend with a 9 sec 3 stage car told me that the nitrous could skew the numbers but I dont know.

 

Running on 93? Using any octaine booster of any type? Sounds like you could have gotten some bad fuel.

 

Yeah, 93 and nothing else. I'm pretty convinced that it leaned out but just cant figure out why.

 

If it was at 19 very long, that's ugly lean. You'll need new plugs anyway, and gap them down .034. Then check why the thing was so flippin lean.
97% DC is pretty high although not disaster. You running bolt ons too?

 

i gapped my plugs at 39 a

 

i gapped my plugs at 39 AND NEVER HAD A PROBLEM

 

Bolt ons and a TR 224/563 cam.

I thing if the AFR really was 19.xx from 1st-3rd gear it wuld have melted the ground strap or electrodes.

 

Sounds almost as if the fuel noid was intermittent.

 

The power came in very hard and was smooth all the way to the very top of 3rd gear, almost like it ran out of gas. I'm planning on pulling all the plugs tomorrow and see how they all look. I took the solenoids apart the day before I sprayed it and everything look good, I also took them apart yesterday and they looked good.

 

i'm almost willing to bet she fattened up on you.. at a 97% duty cycle your indanger of going static on the injectors and them staying wide open. over fueling backfiring out the exhaust then bogging when you pump the throttle.. lean is also possible though.. your gap should be fine and i wouldn't close it any more.. 38 seems to be the sweet spot.. you say you pulled 4* of timing so what was your total timing at??

 

Stock for those timing cells is 28, so I'd sayid should 24*

The thing you said about the injectors going static makes ALOT of sense to me, my friends watching said on the pop on 1 run it shot a 2 foot flame out of the exhaust.

I'm putting new plugs in tonight, so .036 is the min, you dont think the gap needs to be closed anymore?

 

i see no reason to go smaller than .036 on that size shot.. and i don't see you shpitting flames running lean.. sounds like unburnt fuel.. i almost wonder if your nitrous noid started failing.. i assume your noids are on a relay right??

once shes back together go try it with a 1050 bottle and pull a plug out immediately after the run.. see how she looks..

 

I pulled the plugs and changed them, they all looked pretty much the same.
The base was sooty black, the porcelan was very clean and white and the ground strap had 2 marks on it 1 very close to the base and the other close to that one just before the 90* curve. The electrodes all had a white coating on the tip . The only plug that was different was cylinder # 6, everything looked the same as the other plugs except the porcelan was sooty and black.

My fuel and nitrous solenoid are on the same relay. I have the purge on a seperate. I called cold fusion today and asked them for a rebuild kit and they told me they dont make a rebuild kit for them and I should just replace them once a year. I will be buying better solenoids soon. My friend felt sorry for me and gave me a set of Siemens Decca 55# injectors he outgrew, now I just have to figure out how to make drivers because they are low impedance.

 

you say the plugs are white?? hmm.. how much driving is on them since you sprayed last??