power issue

Rob2000gt

Rob2000gt

Donating Member
I have searched for this all over and I cant find anything out about this issue.

When I am at operating temp If i go over 1/2 throttle my boost goes to about 8 psi right away then stays there for 2 seconds then starts to climb to max boost its like its stops accelerating briefly then picks up again. if i stay below 1/2 the power and boost steady climbs. We did some data logging and I have 0 knock my timing is very conservative its mostly a stock truck other than a hot wired pump innercooler scoop and 160 degree stat before I did my reliability mods it would go to 8 drop to 0 go to about 11 so on and so on. I have done a lot of other repairs that were needed to get it running good. we have a low mileage truck at my work that doesn't do this and we have a high mileage truck that doesn't also. I have no check engine light on.

The other issue i have is after I drive it for 30 min or more i park it. If i start it within 2 hours it runs very badly for 30 seconds or till i give it a rev then smooths out. Possibly valve stem seals?
These are the only 2 issues i cant figure out. thanks to the search option I have fixed everything else. Thank you
 
Ty 1885

Ty 1885

Member
Re: power issue

If your valve seals where bad, you'll see blue smoke out of your tail pipe!
As far as your power problems go, first you need to make sure you have 3/4 or more fuel in your tank,
our pick up tubes are located in the middle of the tank, so if you get on it the fuel sluches to the back of the tank, uncovering the pick up and suck air.
Next install a fuel psi gauge. You need to monitor your fuel psi while getting on it.

Let me know how you're making out.
 
berzerker

berzerker

wookie
Re: power issue

when was the last full tune up done ?? My guess is your fuel pump is taking a crap on you . Get a fuel pressure gauge and test psi at idle and driving conditons.
 
Rob2000gt

Rob2000gt

Donating Member
Ty 1885 said:
If your valve seals where bad, you'll see blue smoke out of your tail pipe!
As far as your power problems go, first you need to make sure you have 3/4 or more fuel in your tank,
our pick up tubes are located in the middle of the tank, so if you get on it the fuel sluches to the back of the tank, uncovering the pick up and suck air.
Next install a fuel psi gauge. You need to monitor your fuel psi while getting on it.

Let me know how you're making out.
Click to expand...

I do see smoke only on start up. The reason I was thinking valve stem seals is the oil leaks down onto the plugs. When I restart they are oil soaked and makes it miss till the oil burns off. If it sits for over 4 hours the oil drips off the plugs and it runs perfect but puffs smoke for a few seconds. This is just my theory of what is happening I was hoping someone had this issue on their truck and was able to verify a repair.

It doesn't matter how much fuel I have same issue from full to 1/4 tank(I never go below 1/4 tank) I have hooked up a pressure gauge and monitored it in park but never drove it around I don't want to damage my hose or body closing the hood so I can drive it. It never acts like is sucked up air (it would be a major miss or it would shut down). This is more like something is holding it back for 2 seconds then lets go.

berzerker said:
when was the last full tune up done ?? My guess is your fuel pump is taking a crap on you . Get a fuel pressure gauge and test psi at idle and driving conditons.
Click to expand...

Last full tuneup was a month ago cr43ts msd wires and ac delco cap and rotor
mobil 1 oil
fuel pump and sending unit 2 months ago I believe it was Delphi

I just hooked up my pressure tester
Idle in park 35
idle in drive 37
1/4 throttle 42
1/2 throttle 52 first then drops to 49 then goes to back to 52
full throttle 55 steady for 2 seconds then down to 50 for 2 seconds then back up to 55 and stays there
boost fluctuated with fuel pressure
its seems like a vac leak causing the wastgate and fuel regulator to stall out for a moment but I used a smoke machine to find vac leaks the only one I had was was my egr valve which I replaced at that time. I replaced my map sensor at the same time.
 
Ty 1885

Ty 1885

Member
Re: power issue

Blue smoke on start up is a good indication that your valve seals needs replacement. Before you do anything, you should replace your seals! Oil contamination in the combustion chamber will increase your chance of detonation. You need to stay out of boost untill you fix your oil issues.
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: power issue

The valve stem seals aren't causing your problems. You have the wrong plugs (unless what you wrote is typo) they should be CR42TS. I would change the plugs first.
 
S

Syclone22

Member
Re: power issue

Do you have a wideband gauge installed check
if engine is at temp how the A/F ratios are it
is possible your engine has a rich condition
and will not make boost ..
 
Rob2000gt

Rob2000gt

Donating Member
Well I found why my boost was acting up.. I had a hose that would not seal at about 7 lbs of boost it was a very small leak that wasn't detected with the smoke machine I fixed the issue and now that part is perfect. It really drives great now.

For some reason I thought I read cr43ts is the stock plug. I bought the cr43ts and I bought cr42ts for some reason I just tried to look up where I got the info from and now I cant find it. When I pulled my plugs they were cr43ts so that is what I put in.
 
randy merritt

randy merritt

Donating Member
Re: power issue

You can bring it over here and change the plugs on the lift if you like. Glad the boost issue is resolved.
 
Gnocide

Gnocide

turbo game burt reynolds
Re: power issue

Rob2000gt said:
For some reason I thought I read cr43ts is the stock plug. I bought the cr43ts and I bought cr42ts for some reason I just tried to look up where I got the info from and now I cant find it. When I pulled my plugs they were cr43ts so that is what I put in.
Click to expand...

42s the lower number is the coldest plug offered by gm.
if you like boost stick with it.43 will work but is 1 heat range higher.
 
Rob2000gt

Rob2000gt

Donating Member
Runs so much smoother will post on power in a few days

Update.
I ran the cr42ts at .33 gap did some datalogging. I got over 4000 knocks on the knock counter over a 20 mile ride. knock retard went to 4 degrees at full throttle. definate power loss at full throttle and once in a while i could feel something wasnt right. Spark advance went to 10 degrees at full throttle. I then I put the cr43ts with .25 gap back in, power came back. Knock counter was 448 on the same 20 mile ride 0.0 knock retard. Spark advance drops to 12 for a second then to 14 right away at full throttle. It idles at about 24 spark advance. Thank you Randy for your cable.
 
randy merritt

randy merritt

Donating Member
Re: power issue

Rob2000gt said:
Update.
I ran the cr42ts at .33 gap did some datalogging. I got over 4000 knocks on the knock counter over a 20 mile ride. knock retard went to 4 degrees at full throttle. definate power loss at full throttle and once in a while i could feel something wasnt right. Spark advance went to 10 degrees at full throttle. I then I put the cr43ts with .25 gap back in, power came back. Knock counter was 448 on the same 20 mile ride 0.0 knock retard. Spark advance drops to 12 for a second then to 14 right away at full throttle. It idles at about 24 spark advance. Thank you Randy for your cable.
Click to expand...

When he says cable, he mean my ALDL cable, not what you sick Fu**** were thinking.
 
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