'92 low power

[Bob V]

Hi all. I hope you can help me find the problem with my friends '92 350 automatic 4x4. He recently bought it with 60,000 mi on it. He asked me to look at it because it has low power and sluggish. The previous owner put a Banks kit on it, we are not sure which one. It defiantly is not right. I have changed the fuel and air filters with little difference. He has no boost or pyro gages so I added a temporary boost gage. the max boost is about 12 psi and it takes a long time to get there. Right now he is not looking for enhancements, he just wants it to run right. Any Ideas as to what else too look for before it goes to Cummins? TIA

Bob Verhoef

 

[BushWakr - RIP]

If thats all the boost your getting I'd start by looking at all the turbo connections. Check all the clamps, rubber connector tubes, even the little air/fuel tube connected to the side of the AFC housing.

Also if the truck is equipped with a Banks system, does it have a wastegated turbo housing? If so, then perhaps the wastegate is stuck open/partly open.

Is the throttle opening up all the way, full travel? It should contact the governor screw at WOT. If not then adjustment is needed.

Start there and get back to us with your findings.

Has he checked mileage? If so, what is the mileage. Does the truck start/idle/warm up properly? etc.



Good luck,

Bob

 

[hdm48]

You didn't say if it is smoking or not. And like Bushwakr said, check the throttle to see if it is getting full travel. You might want to look to see if the prior owner turned the pump down for the emissions test. Does it rev up? Is it smooth or does it shake and rattle?



--dave--

 

[J DeMaio]

Hi:



My truck makes 12 to 14 pounds of boost depending on how it's ran. It has a 3" straight pipe and a K&N air filter, a very little bit of fuel. My truck has the stock 21 cm turbine housing, does the truck your working on have a different housing? Is it wastegated or non wastegated? Does the housing say Holset or Banks on it? But normally, my truck makes 12 pounds of boost and is pretty much stock.



Hope this helps,



John

 

[Bob V]

After I changed out the boost gage and adjusted the throttle a little the boost is now at 15psi. It seems that moving the rate pin made the difference. Still can't get it to smoke but I think that it will be OK. I can't find anything on the turbo housing it is non-wastegated, how can I tell which housing I have?Thanks

Bob

 

[BushWakr - RIP]

15 psi is not bad. It sounds like the truck has not been tweaked too much, or atleast its been backed off before sale.



When you removed the AFC diaphram did you have any problems doing so?

Was it a little 'sticky' then popped out?

On some of these trucks the little "metering rod" (my word) that rides up and down on the eccentric can stick and not move properly/fully. Take the AFC out again and look down the hole, then slowly open the throttle ... the little pin should 'pop' out. (not fall out, don't worry)

Use a long, thin blade screwdriver to gently push it back into its little hole and replace the diaphram. I put a little grease on the eccentric roughly were the pin rides up and down.

Generally 12:00 is used to describe the position facing the rocker cover, when leaning over the drivers fender.

Have you seen the little drawing on the AFC, Starwheel, Eccentric, that I posted a while back?



If you're looking to make more smoke, and more power, and more EGT's you can rotate the starwheel clockwise. Mark the 12:00 position as always, then turn the starwheel about 4-5 clicks and drive it. Repeat as necessary.

When you're done you'll have more smoke/power/higher EGT's

You can use the smoke adjustment screw to help with that.



The full power fuel screw is the one adjustment that really makes alot of smoke and power. It increases fuel across the band, bottom end to top end. The thing is, a larger portion of that fuel increase is allocated towards the low boost end. This results in more smoke at early/medium throttle.

Check to see that the lock collar is still on the full fuel screw, if it is then atleast it hasn't been set "wetNwild" before hand.



Sorry if this is long or confused.



Good luck, Bob