02 gt rev limiter?

[Jess_1TUFF2V]

No start/bogging after hitting rev limiter
Hey guys first time posting on here so im sorry if this is posted in the wrong section Some info on the car before stating my issues
Vortech v2 intercooled set up with blow thru hpx maf
Stage 2 cams 39# injectors 300lph bbk fuel pump 410 gear. 5 spd
Anyways on to the headache...
Driving my car the other day and decided to get on it in first gear car spun the tires and hit the limiter for about 3-4 seconds i then shifted into 2nd and kept going full throttle car ran fine until i got to a stop light where the car fell on its face and then would not start. First things i checked were all pipings and couplers to see if they had blown off but nothing every coupler and clamps checked out good..i tried starting the car and it wont start unless i have the gas pedal depressed and when it does starts it acts like its not getting enough fuel boggs out and dies. If i keep the pedal depressed it does rev up and from what i can tell theres no unusual mechanical noises coming from engine but it does leave a strong smell of gas coming from tail pipes. No coolant in oil or none of that either. I then swaped out the fuel rail pressure sensor with a good working one and still nothing. No gas moisture in the vacuum line or gas smell coming from the oil from the filler neck or on the dipstick. Fuel pump primes when key is tuned on. Dont know what else to check for any tips or suggestions is appriciated!!!

 

[Sluggie24]

My guess would be a broken valve spring or a valve floated and hit a piston and bent. Do a compression test on each cylinder and you should find the bad one.

 

[Jess_1TUFF2V]

My guess would be a broken valve spring or a valve floated and hit a piston and bent. Do a compression test on each cylinder and you should find the bad one.

Going to do that test and see what numbers i get. With a bent valve or broken spring wouldnt that cause some loud noises coming from either side of the engine the damage would be in?

 

[Sluggie24]

They wouldn't cause any noise.

 

[Jess_1TUFF2V]

They wouldn't cause any noise.

Ok thanks! Ill get on that compression test and go from there!

 

[jaxbusa]

And look at the plugs closely.


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[Jess_1TUFF2V]

And look at the plugs closely.


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Yeah will be doing that first. Read on another forum a similar situation and turned out to be a handful of melted plugs.

 

[Jess_1TUFF2V]

A quick update. I checked plugs and every single tip of the plug was BLACK. Never seen a set of plugs that bad. I swapped them out and still no change. Next i started to mess around with the mass air sensor. I unplugged the mass air and the car does stay on but at very low rpms, they jump up and down from about id say 200-500 and does not die out and also does not puff out smoke or any raw fuel smells with maf unplugged. Next thing i tried was disconnecting the air inlet tube to the throttle body, (with maf still unplugged) started the car and it started and rev'd on its own to about 3k rpms and held there but it was throwing out white smoke which gave a very strong fuel smell im guessing it was spitting out raw fuel from tail pipes. Didnt get a chance to do the compression test but that is the very next thing ill do to it before messing with anything else. Another thing i noticed is the bov stays closed when everything is buttoned up. Only time it opens now is if i high rev the rpms over 4k and let off itll open up and release some pressure then close right back up.

 

[Sluggie24]

The BOV won't open because the engine can't build full vacuum when a valve isn't sealing.

 

[Jess_1TUFF2V]

The BOV won't open because the engine can't build full vacuum when a valve isn't sealing.

So should i bother with the compression test? Or based on that should i just call it done and start the tear down process?? I guess i can still do it and see what results i get.. on a good note good thing i have a healthy back up motor!

 

[Jess_1TUFF2V]

Also thanks for all the help and replies. Really appriciate it!!!

 

[StalkerStang]

3-4 seconds of rev limiter bouncing? Jeez....

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[Jess_1TUFF2V]

3-4 seconds of rev limiter bouncing? Jeez....

Sent from my SM-G950U using the svtperformance.com mobile app

Yeah ive done that 1-2 shift many times and this time for some reason i didnt shift quick enough.

 

[Sluggie24]

Do the compression tests of each cylinder. Only need 3 compression strokes per cylinder when taking readings. 3 strokes should give you around 125 psi on a good cylinder. A bad cylinder will most likely be 0 psi or extremely low. Test all cylinders to determine if more than one are bad.

After you know which is/are bad, pull the valve cover and look at the valves, springs, cam followers for the bad cylinder. You should be able to see if a spring broke or if a valve is stuck down from being bent. Might have to turn the engine over by hand with a breaker bar on the crank bolt to see those. A bent valve doesn't have to hang open far to do what your engine is doing so you might have to look closely and compare to another good cylinders valves.

If it's a broken spring then the heads don't have to come off if you have the proper tools to replace it while the head is on the engine. If the valve is hanging open then the head has to come off.

I'm curious. With your aftermarket cams did you install aftermarket valve springs? Were the Pistons fly cut to give the valves clearance?

 

[Jess_1TUFF2V]

Do the compression tests of each cylinder. Only need 3 compression strokes per cylinder when taking readings. 3 strokes should give you around 125 psi on a good cylinder. A bad cylinder will most likely be 0 psi or extremely low. Test all cylinders to determine if more than one are bad.

After you know which is/are bad, pull the valve cover and look at the valves, springs, cam followers for the bad cylinder. You should be able to see if a spring broke or if a valve is stuck down from being bent. Might have to turn the engine over by hand with a breaker bar on the crank bolt to see those. A bent valve doesn't have to hang open far to do what your engine is doing so you might have to look closely and compare to another good cylinders valves.

If it's a broken spring then the heads don't have to come off if you have the proper tools to replace it while the head is on the engine. If the valve is hanging open then the head has to come off.

I'm curious. With your aftermarket cams did you install aftermarket valve springs? Were the Pistons fly cut to give the valves clearance?

Yeah i will get that test going and see what numbers i get. So after all that you stated im hoping for a broken spring(s) rather then a bent valve since that would be an easier fix. If its a bent valve i think ill just swap out the motor just to get on the road faster for now rather then tear the engine down then put it back together as the car is(was for now) my daily driver. As far as springs, valves, and pistons all that is still stock. I have the hitech motorsports stage 2 cams which didnt require any of that but better springs are recommended for higher revs. Also i had been running these cams before the supercharger and car ran with no issues and taking it to redline i never had any valve float or any issue of that sort. After the charger install i have hit the rev limiter before, which was kept stock in the tune, amd hadnt experience any issues til now. I guess it finally decided to give out.

 

[Jess_1TUFF2V]

Update!! So after putting the car on the back burner for months i finally got back to it. I swapped out the engine with a healthy motor and added a centerforce clutch paired with a fidanza flywheel and bbk longtubes with catted xpipe aluminum radiator and edelbrok water pump. I buttoned everything up double and trippled check every connection, i go to start the car AND ITS ACTING EXACTLY THE SAME AS BEFORE THE SWAP!! Still no C.E.L is thrown and the car with the maf (vmp hpx5000) unplugged idles for 5-7 seconds surging and i could hear detonation in the cylinders before stalling out. With the maf plugged in the car tunrs over starts up revs to about 1500 rpms but then immediatly dies. Could it be that i fried the maf sensor some how or another sensor causing this very big headache any suggestions and help is greatly appriciated!!

 

[Three21]

With a handheld tuner you could datalog your MAF voltage and AD counts. That could identify a dead MAF sensor.

Have you eliminated fuel issues? Replace your filter and check what fuel pressure you are seeing. Should be 40psi+ at idle.

 

[Jess_1TUFF2V]

With a handheld tuner you could datalog your MAF voltage and AD counts. That could identify a dead MAF sensor.

Have you eliminated fuel issues? Replace your filter and check what fuel pressure you are seeing. Should be 40psi+ at idle.

Have not checked fuel pressure with a gauge yet but i did try a different MAF (same exact one from a cousins car) and car acted the same. Fuel filter was replaced and still nothing. Im thinking maybe the ccrm took a dump

 

[Jess_1TUFF2V]

Another update.
Other then cams and fuel pump i Returned the car to stock form. Although i did drop the tank to check fuel line and connections inside the tank and all seemed fine. Fuel pump primes when key is at on position and reads 40psi but during cranking the psi levels jump around between 20-40 psi. Anyways stock Injectors, maf, spark plugs and tune Went back on the car and still no damn luck!! Still doing the same thing. I also tried replacing the CCRM, FPCM and inertia switch from my last gt(same part numbers on them) and no luck with that either. So can it be a faulty fuel pump or the pcm got cooked somehow? Going to swap the stock pump back in and see what happens then if not a trip to the shop it is!