low power on 93

[ARhine]

Saw there was already one thread going and didn't want to hijack it.



93 W250 with 216K Miles. I put a BHAF on it, clean fuel filter, AFC to deepest setting, fuel screw is as deep as it will go with collar still on it. Stock exhuast with no muffler. Not getting any blowby than normal, doesn't use any oil.



Pulling a 5K lb load.



My 70 chevy with a mildly build 350, TH350, and 3. 42 gears will outpull this thing still.



Towing in KS I get around 19lbs of boost and 1200 egt up a steep hill. Pulling in colorado was a struggle. My EGTs would keep climbing and by the top of a pass I was barely in the throttle in 4th or I had to drop to 3rd where I then could pull easy against the govenor at 2300rpm with a 1200 EGT (traveled accross the state on I70).



Truck gets good milleage is the one good thing. 19mpg empty most of the time. Anywhere from 13-16 towing depending on speed.



Just wished I lived close to an expert on this board. Or is there a good shop in KS I can talk to about this thing. I am in the north central part of the state.



I just finised a complete rebuild of the D70, and now the Getrag is getting noisy to Almost has me depresed about it to the point of just selling it and finding an newer one, but that costs to much money as well.



Andy

 

[bgilbert]

Two things I would check. One boost leaks. 19psi on a modified pump with 5k lbs in tow, sounds low. Check the condition of the intercooler boots, tightness of the clamps, possibly make a leakdown tester with a 4" plumbers cap, schraeder valve and tire patch. Second, remove the afc cover and diaphram again. Cycle the throttle while you look down the afc bore. Check to see that the afc pin pops out when you give it throttle. Sometime the afc pin will start to stick, resulting in low power.

 

[ARhine]

I have new boots on it and a new o-ring on the elbow, but have not done a pressure check on the intercooler. Will give that a try. Will have to stop by the hardware store on the way home and see what I can round up. Any pics of a good test setup?



The AFC pin was popping out of its bore the last time I had the cone out, so that is good.



Sorry for the tone in the orgional post, I just had to vent alittle. I have been working on this thing more than I have been driving it the past 6 months.

 

[bgilbert]

Sounds like you've got everything covered, except intercooler and intake cover bolts maybe. I wish I remember what TDR issue had a pic of the boost leak checker. Basically, a 4" plumber's cap that should already have a 4" band clamp on it. A schraeder - valve stem - valve, and a tire patch kit. You drill a hole small enough to pass the S valve through the cap. Then I think you drill a hole in the tire patch, slip it over the S valve on the outside of the plumbers cap. Use silicone on the tire patch to form an air tight seal over the cap. Place the cap on over the turbo intake, tighten clamps, then add 10psi of regulated air. Use soapy water from a spray bottle, spray on the intercooler, boots, all connections, boost gauge at intake, intake cover bolts etc.

 

[MMiller]

19 lbs of boost sounds low. What does your pyro end up at? Any smoke ever? Check the diaphram and make sure its not torn or a hole in it. I've not heard of any bad ones on a VE, but we fight it from time to time on Cat injection pumps. The diaphram will leak boost, and then the pump does not give any fuel as it does not see boost.





Michael

 

[ARhine]

If I push the pedal to far before the boost comes up, say mash the pedal in 3rd at 1200 rpm, I get a big fog of black smoke. Once the turbo spools up though around 1500 rpm I don't get any more smoke. When I changed the AFC setting I did notice the EGTs come up quicker though so it must be moving. I haven't messed with the starwheel or smoke screw settings.



Driving at altitude I had to be carefull and watch the EGTs pretty close or they would be right up to 1250. Basically if my rpms got below 1800 I had to grab the next lower gear or my EGTs got out of control.



Since my rig has AC it is going to be more difficult to spray soapy water on the IC, I guess I will just have to to a leak down test instead.

 

[dpuckett]

Sounds like a fuelling issue

Have you had your injectors checked? I've had a few that had bad injectors (carboned up- nothing super bad), and getting them cleaned and reset for pop pressure made a WORLD of difference. Boost pressure went up, EGT dropped, and climbed slower. If yours are stock, I'd start there. Pump could be getting tired, too. If the RPM advance isnt wroking properly, you'll get high EGTs along with your low boost.



Daniel

 

[ARhine]

When I bought the truck the PO said he had had the injectors out and tested about a year before I got it, so I am just going on his word that they are good. It starts quick and the milleage is good.

 

[ARhine]

Ok bought a 3" and 4" rubber pipe cap. the 3" is way to small, the 4" is way to big. I guess I assuemed you were putting these over the inlet of the turbo, am I wrong or are these the wrong pieces? They are marked as "4 inch cap for plastic or cast iron" It actually measures over 4" ID since it is made to go over the outside of the pipe it looks like.



One thing I did notice while I was messing with it is that there is quite a bit of side to side movement in the turbo bearings. I can't get the impellers to rub the housing though. But by guessing without my dial guage handy I would say there is almost . 5mm of movement. No end to end movement detectable though. Supose I am almost due for a turbo rebuild as well. Gonna have a new truck before I know it.

 

[TKingsbury]

Just for a reference, my truck makes 24psi max. I believe mine is very similar to yours, 14cm housing, fuel screw bottomed against collar, and cone full deep.

Travis. .

 

[ARhine]

mine has the 18 yet, but sounds like i have some sort of boost loss.



Maybe I could find parts to test easier by pulling the elbow off and coupling to the pipe going to the intercooler?

 

[TKingsbury]

I guess I was mistaken, I thought you said you had a 14 housing sometime in the past? 'ell if I know. When I had my 21, I was making about 15psi with stock settings.

Travis. .

 

[ARhine]

Got to thinking maybe I should check the valve clearances. Any chance that might help? Going to goto the hardware store again today and try again on the pressure test setup.



Also think I found a guy with the dial tool to check timing. What should I have it set to? This trucks primary duty is towing a trailer.

 

[NIsaacs]

Take the locking collar off the power screw and turn it in some more. Some pumps take a lot of turning. Also, your pump timing might be a little slow. Even with stock injectors, that pump should be capable of make'in that Chevy 350, look sick!





"NICK"

 

[dpuckett]

Vales will make a BIG difference in performance. I have been setting mine to . 009 and . 019 for 2 years on all our pickups, and they seem to idle smoother and be a bit more responsive. But when you are starting at an average of . 018 (intake) and . 025+ (exh), you have nowhere to go but up.



Timing- I'd say with stock injectors- around 1. 4-1. 5mm of lift. See if the guy would be willing to rent it out- there are a lot of guys that are interested in doing their timing up right. If he wont loan it out, I completely understand. Also verify that your tiing pin is at TDC- somce are off by up to 5deg. Fine for valve lash, but useless for timing.



Daniel

 

[MPalmer]

with mine i can make 32psi and hold it there with the 21 housing on the stock turbo and the last 2 weeks no matter what i did i could not get over 20psi i had high egt's really bad mpg and all i got was alot of smoke then one nite i got the idea to take the pipe off the turbo and test it with no filter and then my boost was back up to 32 the egt was way down and not burnin as much fuel so i got a new filter and it fixed my low power/low boost problem.

 

[ARhine]

My BHAF ony has around 8k miles on it now and looks clean.



I don't think I should be turning the fuel screw up any more at this point. When in colorado I couldn't use over half throttle anyway, the EGTs went up to high.



I got some more pieces at the hardware store that I think will work to test the IC and hope to have time to get it done today.

 

[ARhine]

so I am hosed here?



I rigged up the pressure test tonight. Couldn't build any pressure in the system. Thinking man I got a big leak! Happen to walk past the tailpipe and hear air..... all the air is flowing out the tailpipe. The way I have it hooked up I took the elbow off the turbo and put some plumbing adapters in the first boost boot.



What now?

 

[MMiller]

You need to cap off the other end where it goes into the intake to test the aftercooler. All your air is traveling down through the engine.



Michael

 

[ARhine]

After a drink of water I decied to go back out. Pulled the wire to the shut off solenoid and bumped it once. No more (or very little) air out the pipe.



I built my rig with a regular automotive valve stem and it took a while to build pressure. I was getting a flow out the blowby I could feel and built decent pressure in a few seconds with my thumb over the hole (later with the rig running at 2K rpm there was very little flow at all)



Found one loose band clamp. With it pressurized to around 15psi it took 30 seconds to get back down to zero, my guess is a good portion of it through the blowby. So it seems there is no large IC leak?



Where next. I might spend the money to build another plug and test just the IC by its self.