[mrhockey]

This just started tonight. I didn't change anything. I got two runs in before it happend. The first was OK and the 2nd was still good and the ET was decent considering track conditions. The 3rd & 4th runs started the surging. Same exact time and same exact surging. The graphs overlap identically. It was before the shift at around 7100 RPMs. Any ideas? First stage on right at the hit and the 2nd is on a progressive starting at .9 and is all in by 1.7. Right after that at around 1.85 the surging starts. Timing is OK, Digital 7 program tree is OK, crank trigger pick up checks out ok, distributor cap and rotor are ok. Not sure if some gremlins got into my computer or digital 7 or my Edelbrock progressive or what. Photobucket won't upload it because it is not a JPG.

 

[Seattle_Mike]

Are you logging your nitrous pressure? I mention it because you said the first two runs were fine and then it started. Low nitrous pressure can cause surging.

 

[mrhockey]

No I don't log that yet but the bottles were full. I always use a new bottle on every pass and the starting pressure is always 900 pounds. Also the battery was charging 13 volts+ as usual. It is a 12V system.

 

[notsobroke]

check the basics make sure your filters on you nitrous aren't clogged. check your plungers(make sure you have teflon ), make sure your fuel reg is hold pressure and not creeping.

 

[dennysavage]

This just started tonight. I didn't change anything. I got two runs in before it happend. The first was OK and the 2nd was still good and the ET was decent considering track conditions. The 3rd & 4th runs started the surging. Same exact time and same exact surging. The graphs overlap identically. It was before the shift at around 7100 RPMs. Any ideas? First stage on right at the hit and the 2nd is on a progressive starting at .9 and is all in by 1.7. Right after that at around 1.85 the surging starts. Timing is OK, Digital 7 program tree is OK, crank trigger pick up checks out ok, distributor cap and rotor are ok. Not sure if some gremlins got into my computer or digital 7 or my Edelbrock progressive or what. Photobucket won't upload it because it is not a JPG.

Check the bottles from the "Surge" runs. Pick on up, and hold it end to end, and shake it back and forth. If it goes "Tink,Tink,Tink", the siphon tube could be loose. This will make it Suuuurrrrge. I had this happen to me before. Chased it for a long time...
XNITROUS DAWG
PS- This is easier to detect when the bottles are empty... At least, not full..

 

[mrhockey]

Thanks guys.

Denny I used a different bottle on each pass. I switch after each pass so that is unlikely. Again the two surges on the graph are DEAD ON mirrors of each other. It looks like an EKG but the RPMs are gradually going up at each peak, maybe 50 RPMs or so so I don't think it is some type of rev limiter. I don't think it is any wiring or bad relay or short because it happens at exactly the same point. My engine guy said to double check valve springs for a broken on but I didn't get home till about 2am and off to work at 5:30 so I will check that when I get home first.

Notsobroke, do you have an LSM type valve spring compressor in case I need one tomorrow?

 

[gimmemud]

Did you look @ the plugs after either of the runs, sounds like to me its getting pig rich when the 2nd stage is all in.

 

[dennysavage]

Thanks guys.

Denny I used a different bottle on each pass. I switch after each pass so that is unlikely.
That's why I said check bottles from the surge runs...
Lots of people overlook this...
Denny

 

[notsobroke]

Thanks guys.

Denny I used a different bottle on each pass. I switch after each pass so that is unlikely. Again the two surges on the graph are DEAD ON mirrors of each other. It looks like an EKG but the RPMs are gradually going up at each peak, maybe 50 RPMs or so so I don't think it is some type of rev limiter. I don't think it is any wiring or bad relay or short because it happens at exactly the same point. My engine guy said to double check valve springs for a broken on but I didn't get home till about 2am and off to work at 5:30 so I will check that when I get home first.

Notsobroke, do you have an LSM type valve spring compressor in case I need one tomorrow?

i use a jesel type on my car. and have this crappy one for stock stuff not sure if it will help you let me know

 

[notsobroke]

hell i have the moroso one as well for stud mount

 

[mrhockey]

Thanks Rich. I will keep you posted. PM me your number or bring them along in case I am in a bind.

Denny, I will check the bottles but that would have been two bottles that suddenly happend to?

Mud, it did look rich but not sure why the graphs would be identical as to the frequency of the peaks and valleys and to the exact RPM to the single digit. I wish I could post it.

All good ideas and stuff I will look into. Looks like I will be entering the 8.50 index tomorrow and trying to work the bugs out at the track.

 

[gimmemud]

How much difference was there in the air compared to the last time you ran it before the problem, if the air is horrible I usualy drop a lb or so from th second kit. Lean is way better than fat, just like women

 

[gimmemud]

I dont think it would be valve springs, valve float would show signs like popping out the headers or through the intake, depending on whether its and intake or exaust spring.

 

[z289sec]

Totally Different

I know yours is a totally different setup than mine, but you did say the second kit was on a progressive. I use the teflon seal plungers in mine and when they get worn from being pulsed a lot they do that on mine. I can change the plunger and it goes away.

I know this is simple and goes without saying, but have you tried running on just the first kit to eliminate one kit or the other? That way at least you have a focal point for the problem.

 

[wazslow]

I know yours is a totally different setup than mine, but you did say the second kit was on a progressive. I use the teflon seal plungers in mine and when they get worn from being pulsed a lot they do that on mine. I can change the plunger and it goes away.

I know this is simple and goes without saying, but have you tried running on just the first kit to eliminate one kit or the other? That way at least you have a focal point for the problem.

Were gonna try that at cecil tomorrow...

 

[Mike Thompson]

I know yours is a totally different setup than mine, but you did say the second kit was on a progressive. I use the teflon seal plungers in mine and when they get worn from being pulsed a lot they do that on mine. I can change the plunger and it goes away.

I know this is simple and goes without saying, but have you tried running on just the first kit to eliminate one kit or the other? That way at least you have a focal point for the problem.

I have to agree with this statement.

 

[n20mstr]

check the plungers!! ! If you can, measure how much the center is pushed up, after they get to .015 you need to change them. Also check any nitrous filters..

 

[mrhockey]

Remember this post?

http://www.yellowbullet.com/forum/showthread.php?t=66880

I am wondering if this problem is a progression of what might have started here with the strange RPM graph and has now gone over the edge into a full fledged problem?

I have a problem believing it is springs too because it is too perfect and precise of an identical graph to the time and rpm when the two are overlayed. I will check the plungers too tonight. If it is the plungers once there is fuel and nitrous pressure against them wouldn't it leak through as soon as it is on? That would have started at the beginning of the run and not our further??? Yes? No?

 

[gimmemud]

Remember this post?

http://www.yellowbullet.com/forum/showthread.php?t=66880

I am wondering if this problem is a progression of what might have started here with the strange RPM graph and has now gone over the edge into a full fledged problem?

I have a problem believing it is springs too because it is too perfect and precise of an identical graph to the time and rpm when the two are overlayed. I will check the plungers too tonight. If it is the plungers once there is fuel and nitrous pressure against them wouldn't it leak through as soon as it is on? That would have started at the beginning of the run and not our further??? Yes? No?

What was the outcome from this problem, was it ign. box related?

 

[n20mstr]

look at the plunger from the side, youll see the center may be pushed up, measure the center then measure to outside the ring dimpled in, Im pretty sure (depending on the brand of sol) that the plunger only lifts .040 or .050 off the seat, so if the center is raised up .015 or more its quite restirctive, pressure and progressives beat up the plungers, Just one more thing to check...

If the center is raised its not going to leak, unless its torn up, the raised part just restricts the flow