2G Rpm go crazy when hitting boost

[jmonterful]

As my tittle says once i hit boost my rpm gauge starts going crazy up and down can it be a boost leak? Running rich? What you guys think i think it might have something to do with the gas because one time i started to run out of it cause my gas gauge didnt work and started doing something similar if not the same thing but once i put gas srarted working fine now it happens only when i hit boost. It was running fine that same morning but at night started with that. Any ideas what can or should i do? Thanks in advance. I'm not sure how much boost am running it hasnt been tunned i just have a 20g if that matters.

 

[rival]

what are you running for fuel mods?

 

[oneslowwdsm]

The needle itself starts going crazy? We might need a video of this one..

 

[jmonterful]

Everything fuel is stock am planing on upgrading the fuel i got bigger injectors but i wanna wait until to put it on until i got money to tune it and buy ecmlink to do it all at once. I had a problem with it cutting at really high boost but now is anywhere i hit boost & yeah my bad the needle starts going up and down and
everywhere and the car starts to cut then wants to go then cuts again and so on. i'll try to make a video to show you guys whats going on once i get off work. Thanks guys

 

[greddy_1700]

So many issues with this one... First of all running a 20g turbo with no fuel control, it must be cutting incredibly hard. Secondly, it sounds to me like a cam / crank angle sensor

 

[Justin Lauscher]

Maybe your clutch is slipping?

 

[luv2rallye]

I assume you're talking about the stock tach gauge? That only runs off the power transistor (PT). So unless you've got a bad PT or something's making the ignition cutout, the tach is unaffected by boost. Sounds like the ECU may be hitting fuel cut which cuts off fuel and ignition (perhaps because of the 20g with no fuel mods to support it). See: http://members.shaw.ca/costall/ECUprimer/ECU_ch7.html for explaination.

 

[rival]

thats what i was thinking luv2rallye......

 

[farmer890]

Been through this exact thing early on with mine. You're hitting fuel cut big time. Turn down the boost until you pimp out your fuel set up to feed that 20g.

 

[jmonterful]

Okay, so most probably from all this must be the fuel cut i'll look into fixing that. But how could you explain the car was running okay earlier what you guys think happened?

 

[CivicdailyTalonbaby]

Possible boost spike? O2 housing could be the cause.

 

[Boomdeeze]

I don't think it was on my tach but in my logs I was having the same issue. When I would hit about 5.5k, ECMLink would randomly jump up to 10k-12.5k causing a very bad backfire/mis-time. Long story short, I found out it was the connector for my 1G CAS had one or two wires that were loose inside the connector. The vibrations would hit just right and cause the wire to shake which made it send an incorrect signal.

Then again with the lack of fuel upgrades, I would start with fuel cut. This is just another idea to test.

 

[pauleyman]

Been through this exact thing early on with mine. You're hitting fuel cut big time. Turn down the boost until you pimp out your fuel set up to feed that 20g.

Fuel cut has nothing to do with availability of fuel.

 

[pauleyman]

As my tittle says once i hit boost my rpm gauge starts going crazy up and down can it be a boost leak? Running rich? What you guys think i think it might have something to do with the gas because one time i started to run out of it cause my gas gauge didnt work and started doing something similar if not the same thing but once i put gas srarted working fine now it happens only when i hit boost. It was running fine that same morning but at night started with that. Any ideas what can or should i do? Thanks in advance. I'm not sure how much boost am running it hasnt been tunned i just have a 20g if that matters.

Lots of suggestions.....let's think about this.

If the tach is jumping all about it can't be physical. That rules out all drive train and motor parts. Couldn't be clutch, boost leak, o2 etc. Not possible. Electrical is likely the culprit. As suggested cam or crank sensor. You didn't really say if this affects how the car is running. Do logs reflect this same rpm change?

 

[DSMNewbie1986]

Check your trans. speed sensor on the back of the tranny. Sounds electrical but a 20g will definitely cause fuel cut without supporting fuel mods not to mention good old boost creep.

 

[pauleyman]

Check your trans. speed sensor on the back of the tranny. Sounds electrical but a 20g will definitely cause fuel cut without supporting fuel mods not to mention good old boost creep.

How does fuel cut have anything to do with a flaky tach? Real question.

 

[jman1699]

Do you have a 2 step programmed. A vss went bad on me once and would bounce of my two step

 

[jakk220]

I have noticed a slight issue with the tachometer on my 1g as well. I haven't had it that long so haven't messed with it but it seems around the 3-4k rpm range it kind of jumps up really fast and then bounces around falls back down. Its all a pretty fast quick motion and then it goes back to normal. The engine doesn't act any differently or sound different though so I'm almost positive that its electrical.

 

[gsxrunning]

Fuel cut, no reason to be boosting over 10 psi on stock fuel setup.

 

[gsxrunning]

Also make sure you have good connections hooking up to your tach. May have a loose wire and when you get into boost. It may be just enough.

 

[jmonterful]

Car is running better now it just doesnt want to hit boost anymore. It builds it and the bov sounds but u wont feel anything. I'll try looking at it tonight at someone's shop i'll keep you guys updated. Thanks for the posts