Voltage Drop/Struggling Revs

[Scoobum]

This car of Dan Kellers is possessed. I'll get you guys up to speed. Engine is rebuilt. Had Dan at track with me Saturday. I jumped in the passengers seat and watched the PL as we went down the track. Boost is 21 pounds and 02's were 790 going thru the traps...zero KR. Revs topped out around 4600...and it struggled in every gear to build RPM. Volts are in the mid 13's...until he gets into boost...and then they drop to low 12's. Battery/alternator are new. New Racetronix fuel pump and hanger. IDC is 95 percent...and injectors are new 60's with matching TT chip. I can give you any other info from PL...so fire away...cuz this car is driving me nuts.
P.S. His personal mechanic works on the car...not me. The car feels like the timing is retarded. Is it possible if he didn't put the 1.5" timing tape on the balancer...and then move it around when setting the cam sensor...would this be the issue...or would it even start?
 
 P.S. 2. New hotwire kit as well.
 
P.S. 3. It pops the fuel pump fuse frequently he told me.
 

[Steve Wood]

does not sound like it went lean with those o2s.

rig a volt meter directly to the back of the alternator and see if the voltage drops instead of watching the scan tool.

If it drops on the volt meter, then it would sound like the alternator is bad.  Frequently happens because the output is low and cannot sustain the voltage when the load comes on.  On the other hand, scan tools often reflect a voltage drop that has nothing to do with the alternator as there are a lot of connections between the alternator and the ecm that can be flaky...that is the reason we need to know the voltage coming directly out of the alternator.

As far as the fuel pump fuse blowing...wors t case that could be a bad pump that suddenly draws a lot of current when it has to respond to a load...Or it could simply be a short in the oil sender harness down the front of the engine, the wiring to the pump, or in an injector harness feed that is grounding out against the egr, the coil mounting bracket...or somewhere in the feed from the ecm to the injectors....

sounds like more than one problem to me, but maybe not

[Scoobum]

Steve if he makes it to T and T this Friday I'll get him to brake boost it in the pits and I'll check for a voltage drop. I honestly don't think it's the alternator cuz if I remember correctly back to last spring...it was doing this voltage drop with the old alternator. Is the low voltage causing the rev issue in your opinion?

[Steve Wood]

It can make the ignition weak if it drops low enuf.

It's important to know where the drop is and if it drops at the alternator, I would swap another alternator to see if that fixes it.  that's Easy.  IF it stays the same (goes low) then you need to get some idiot kid to ride on the back bumper with a clamp on ammeter to see if the pump is pulling the expected amperage. 

If this is the car with the friggin' double pumper on it, it is important that the hot wire kit is at least 10 gauge because two pumps can pull a lot of juice under boost.  Current shoots up when the pumps are making a lot of pressure in response to boost.

Even tho the o2s look good, the only way to definitively check the pump or pumps is to put a fuel pressure gauge on and watch it under boost to be sure it reads the correct pressure on the top end and neither drops, or spikes above the correct amount.

and, if the voltage drops at the boost where the second pump turns on...if it is a effin' double pumper...then that would be a good clue

[Scoobum]

Single pump. This is a nice car that hasn't been butchered or tampered with. Definitely has some gremlins tho. I'll get as much info as I can as the week progresses. The engine grenaded last spring...and he just got it back to the track this past Saturday.

[YGspider]

Valve springs? 
 
But This sounds very familiar maybe a wiped cam, Also I've swapped my cam sensor with a extra brain harper had and it made no effect on anything. Some say that once you have the car running just unplug it and take a spin and that's a easy way to check. Also have you swapped your coil pack and module with him to see if maybe his module is fried. And last three things are unlikely but I've read into convertors and timing chain jumping causing a lack of rpm but if that chain jumped you would hear it, And a plugged up muffler as the baffles sometimes crumble and restrict your flow.
Also make sure that the powerlogger has good connection as the runs we did at SMP where trash after I reviewed them at home I seen that my PL wasn't getting good connection. So I took a razor and cleaned the connectors now my readings are accurate.
 
What can I say these cars are so Bull shit sometimes but I still love them..   

[YGspider]

It can make the ignition weak if it drops low enuf.

It's important to know where the drop is and if it drops at the alternator, I would swap another alternator to see if that fixes it.  that's Easy.  IF it stays the same (goes low) then you need to get some idiot kid to ride on the back bumper with a clamp on ammeter to see if the pump is pulling the expected amperage.

Intresting maybe I should also try a new ALT b4 I throw some cash into a rebuild. 

[larrym]

I went with a power bastard 140 amp cleared up any issues I had, plus added a couple of extra stout grounds at the battery to the fender and the engine to fire wall.

[Scoobum]

Valve springs? 
 
But This sounds very familiar maybe a wiped cam, Also I've swapped my cam sensor with a extra brain harper had and it made no effect on anything. Some say that once you have the car running just unplug it and take a spin and that's a easy way to check. Also have you swapped your coil pack and module with him to see if maybe his module is fried. And last three things are unlikely but I've read into convertors and timing chain jumping causing a lack of rpm but if that chain jumped you would hear it, And a plugged up muffler as the baffles sometimes crumble and restrict your flow.
Also make sure that the powerlogger has good connection as the runs we did at SMP where trash after I reviewed them at home I seen that my PL wasn't getting good connection. So I took a razor and cleaned the connectors now my readings are accurate.
 
What can I say these cars are so Bull shit sometimes but I still love them..   

Your problem is valve springs...and until you change them your issue won't go away.
 
 

[daveismissing]

Turn on everything in the car , headlights, heater blower rear defrost when you  rev it up for test.
Check the Ac volts too as discussed.

[Scoobum]

Will do...and thanks.