Blocked Air Cleaner Inlet?

[TurboDiverArt]

Hi All,

Very strange. I have a UNI foam air cleaner on the truck. On two different occasions while towing I have noticed that on a long high RPM pull that all of a sudden I

[DA BIG ONE]

I'd suggest that you remove that filter box top when this happens to see if there is a change. However, if the sensor shows the filter needs replacement there maybe a filter issue even though you've cleaned it...........

I've seen oil socked intake filter adapters collapse blocking air to inlet at turbo compressor under boost.

But, then maybe a rat has taken up residence in your fender and built a nest not uncommon........

Good luck!

[JohnC]

Sounds to me like the PCM is detecting overboost and dropping the vacuum to the wastegate controoller. Unless you have some non-standard programming or a boost "fooler", 10-12 psi is more than it wants to see....

(On re-read, I see you have a turbo master. Do you have a stock PCM? If so, try backing the boost off a hair.)

[big61fourby]

Isn't there a resistor trick to fool the stock computer? (I'm thinking $1.00 Radio Shack piece)

I'm searching for a solution to the exact same problem...

BTW, how do you like the UNI?

[a5150nut]

A potentiomitor (sp) wired across the boost sensor. At around 9 ohms you should see 11 lbs boost on your gage and the computer still sees normal. Mine will run 3 lbs cruising at 65 and hit 10/11 under load. Instead of putting it under the hood where you have heat and moisture to worry about, I put mine next to the ECM. Just trace out the wires and follow them back into the dash. Makes it easyer to adjust to.

[TurboDiverArt]

I'd suggest that you remove that filter box top when this happens to see if there is a change. However, if the sensor shows the filter needs replacement there maybe a filter issue even though you've cleaned it...........

I've seen oil socked intake filter adapters collapse blocking air to inlet at turbo compressor under boost.

But, then maybe a rat has taken up residence in your fender and built a nest not uncommon........

Good luck!
Where exactly is the air sucked into the fender? I have modified the air box a little to maximize the air inlet to allow as much to flow through the fender into the air box. There's a little you can trim to increase flow. It's only a little and probably only helps a slight bit but I always figured every bit helps. I did this years ago.

If there is something blocked in the fender I assume the only recourse is to remove the fender to clean it out?

Art.

[TurboDiverArt]

Sounds to me like the PCM is detecting overboost and dropping the vacuum to the wastegate controoller. Unless you have some non-standard programming or a boost "fooler", 10-12 psi is more than it wants to see....

(On re-read, I see you have a turbo master. Do you have a stock PCM? If so, try backing the boost off a hair.)
I have a turbo master manually controlling the boost. Also a boost fooler that allows 14-16 psi of boost before throwing a code.

Art.

[DA BIG ONE]

Where exactly is the air sucked into the fender? I have modified the air box a little to maximize the air inlet to allow as much to flow through the fender into the air box. There's a little you can trim to increase flow. It's only a little and probably only helps a slight bit but I always figured every bit helps. I did this years ago.

If there is something blocked in the fender I assume the only recourse is to remove the fender to clean it out?

Art.

Air is sucked into front of fender and below lights. Some trucks had a plastic snorkle type device I'm guessing to reduce intake noise. First remove grill, area is large enough to use metal coat hanger and twist the end into a 1" to 2" diameter screw put a rag onto the screw end (like an old type gun barrel cleaning rod) and push into opening and upwards, have someone look at the opening at the airbox for the rag.

I'm thinking it's not an overboost situation cause egt's are climbing.....

[ECMProgrammer]

[QUOTE=TurboDiverArt]Hi All,

Very strange. I have a UNI foam air cleaner on the truck. On two different occasions while towing I have noticed that on a long high RPM pull that all of a sudden I

[Mark Rinker]

...or turn down the boost.

Personally, I think a stock 6.5 should be limited to 12psi peaks (loaded and full throttle acceleration) and about 6-7 nominal at 60-65 cruise.

High boost can see falsely lower EGTs even though you are stressing piston crowns and rings from the uneccesary high cylinder pressures.

Oil use will increase as a function of blow-by if you are running too much boost, another good indicator. Are you using oil?

[TurboDiverArt]

Air is sucked into front of fender and below lights. Some trucks had a plastic snorkle type device I'm guessing to reduce intake noise. First remove grill, area is large enough to use metal coat hanger and twist the end into a 1" to 2" diameter screw put a rag onto the screw end (like an old type gun barrel cleaning rod) and push into opening and upwards, have someone look at the opening at the airbox for the rag.

I'm thinking it's not an overboost situation cause egt's are climbing.....
I don't think it's an over boost either. I have a manual turbo master controller. I would think that if it was an over boost because my POT is not set right maybe the truck would cut timing and fuel. Either way the EGT's should drop. They climb very quickly.

Next time I have the trailer hooked up I'll go out and try to reproduce it on the highway. I think if I enter a highway slow and then hammer it I'll have a long haul up to highway speed, should be able to reproduce it. If I can reproduce it repeatedly I'll pull off the air box top.

Thanks!
Art.

[TurboDiverArt]

It's common--you're running into the maximum boost allowed 'timer' that's hard coded to the ECM. The only way around it is to reprogram the ECU.

Lyndon
www.ecmprogrammer.com
Westers garage
1-888-WESTER-1
I think this might be true if I have the POT set wrong (boost fooler). I'll have to look. I have a mark that allows 16 psi without generating a code. Setting it here would allow the ECU to be fooled and generated 16 psi when I had the factory ECU-controlled wastegate installed. Since I don't have the factory wastegate setup and it's manually set, I think the factory ECU would only be able to adjust fuel and timing. I'm not sure if cutting fuel and/or retarding timing would make the EGT's go up and the exhaust pressure drop enough to make the turbo produce zero boost.

Art.

[TurboDiverArt]

...or turn down the boost.

Personally, I think a stock 6.5 should be limited to 12psi peaks (loaded and full throttle acceleration) and about 6-7 nominal at 60-65 cruise.

High boost can see falsely lower EGTs even though you are stressing piston crowns and rings from the uneccesary high cylinder pressures.

Oil use will increase as a function of blow-by if you are running too much boost, another good indicator. Are you using oil?
Cruising unloaded at 65 MPH I'll pull about 3.5 psi. Towing 5000# I'll pull about 5-6 psi. If I'm standing on it I'll get about 12 psi loaded. Unloaded, standing on the gas will usually only get about 10-11 psi. Typically my truck is running at about 3-4 psi.

Art.

[JohnC]

OK, I re-read everything. My comments don't make sense given that you do not have vacuum controlled boost.

When you say "boost plummets" what do you mean? From 12 psi to what?

Given that you're tripping the air filter monitor, I'm thinking something in the air intake path must be collapsing causing too much vacuum in the filter box. Can't think of anything else that would account for the sudden change.

[Mark Rinker]

Are you CERTAIN that your air filter isn't plugged?

A few years back, I had this same scenario with my '94, checked everything (twice) and finally realized that the OEM paper filter was road salt soaked and dried, causing it to restrict airflow. Since the salt was white, it looked fine, but would not flow air properly...

[Bnave95]

When you reach that 10-12 boost range and it drops the boost, truck will smoke like a steam Eng. unless fuel is being pulled. If fuel was pulled then why would EGT go up? Other Than still being fueled with no boost. The filter cause still make no sence.
Does the Turbo Master rod still move with out binding when the spring is pulled? If it pulls and hangs up you'll lose your boost and then maybe free it self.
If that rod get alittle twisted it will bind.

[Trek 6.5 TD Pusher]

I have a 95 6.5 TD in a pusher motor home. It has a max-e-tork chip, a GM-8 turbo, a Heath Turbo Master, and an intercooler. It has an aftermarket cone filter as a prefilter before the Uni Filter. I has a problem simular to yours. Afrer a few miles when the engine heated up, under load with 10-12 lbs of boost, boost would suddenly fall to 1-2 lbs. Checked for boost hose problems several times but could not find anything wrong. Raised the bed so we could watch the engine compartment and had the wife watch while this happened. She discovered that the rubber elbow going from the filter box to the turbo was colapsing. This was due to the pre filter being clogged. Cleaned the prefilter and all was well. This would only happen once the engine compartment was good and warm and it was under load. Each time you stopped and looked for the problem, it would be OK for a short time but would return. Pushers are exposed to a lot of dirt when on dirt roads and it had been at the lake all summer, just going back and forth to the lake from the storage facility. The filter had a lot of dirt in it, but just looking at it while mounted, it didn't look stopped up.

[TurboDiverArt]

OK, I re-read everything. My comments don't make sense given that you do not have vacuum controlled boost.

When you say "boost plummets" what do you mean? From 12 psi to what?

Given that you're tripping the air filter monitor, I'm thinking something in the air intake path must be collapsing causing too much vacuum in the filter box. Can't think of anything else that would account for the sudden change.
Plummets = goes from 12 psi to zero in a few seconds. Lose power, not stalls but loses power and the EGT's start climbing.

I agree, my thought is that either my fender has a blockage, UNI air cleaner is collapsing or the factory air cleaner to turbo tube is collapsing.

Art.

[TurboDiverArt]

Are you CERTAIN that your air filter isn't plugged?

A few years back, I had this same scenario with my '94, checked everything (twice) and finally realized that the OEM paper filter was road salt soaked and dried, causing it to restrict airflow. Since the salt was white, it looked fine, but would not flow air properly...
It certainly could be but when it happened I had cleaned and re-oiled the filter no more than 750 miles prior. I know this because I was driving 500-miles down to pick up a new car. I soaked the filter with filter cleaner, let it sit for a few minutes and then rinsed it with water. I dried it and than re-oiled it the night before I left. Towed an empty trailer 500-miles down and then on the way back I noticed it was happening. It happened again this past weekend when I was picking up a new enclosed trailer and accelerating onto the highway. I can certainly inspect the filter.

My plan to diagnose the problem is to try to recreate this problem while towing my trailer. The problem seems to need a long loaded pull at close to full throttle. If I can reproduce it I'll pull off the air-box top, that would rule out a fender blockage. I do have a brand new paper air filter. If taking the air-box top off still reproduces the problem I'll change out the UNI filter and put on the stock filter and try again. If it still happens with the air-box top off and new filter then I sort of assume the tube is collapsing. Maybe I

[TurboDiverArt]

When you reach that 10-12 boost range and it drops the boost, truck will smoke like a steam Eng. unless fuel is being pulled. If fuel was pulled then why would EGT go up? Other Than still being fueled with no boost. The filter cause still make no sence.
Does the Turbo Master rod still move with out binding when the spring is pulled? If it pulls and hangs up you'll lose your boost and then maybe free it self.
If that rod get alittle twisted it will bind.
When it has happened I never thought to look at the exhaust to see if it's black. Not sure why I never thought to do that, probably because when It happens I

[TurboDiverArt]

I have a 95 6.5 TD in a pusher motor home. It has a max-e-tork chip, a GM-8 turbo, a Heath Turbo Master, and an intercooler. It has an aftermarket cone filter as a prefilter before the Uni Filter. I has a problem simular to yours. Afrer a few miles when the engine heated up, under load with 10-12 lbs of boost, boost would suddenly fall to 1-2 lbs. Checked for boost hose problems several times but could not find anything wrong. Raised the bed so we could watch the engine compartment and had the wife watch while this happened. She discovered that the rubber elbow going from the filter box to the turbo was colapsing. This was due to the pre filter being clogged. Cleaned the prefilter and all was well. This would only happen once the engine compartment was good and warm and it was under load. Each time you stopped and looked for the problem, it would be OK for a short time but would return. Pushers are exposed to a lot of dirt when on dirt roads and it had been at the lake all summer, just going back and forth to the lake from the storage facility. The filter had a lot of dirt in it, but just looking at it while mounted, it didn't look stopped up.
That certainly makes a lot of sense. It's probably something like that. I just need to figure out which.

Art.

[DA BIG ONE]

I'm running a K&N w/pantyhose as pre-filter this setup has been caked w/sand and has never had any problems whatsoever. My boost is around 14.5psi pre aircharge cooler and about 12.5psi after cause of pressure drop, IMHO the pressure drop is too much.........Perhaps it's that fancy filter you have giving you a problem, pull it off install double layer of panythose over intake then drive it to see if problem goes away.........

[TurboDiverArt]

I'm running a K&N w/pantyhose as pre-filter this setup has been caked w/sand and has never had any problems whatsoever. My boost is around 14.5psi pre aircharge cooler and about 12.5psi after cause of pressure drop, IMHO the pressure drop is too much.........Perhaps it's that fancy filter you have giving you a problem, pull it off install double layer of panythose over intake then drive it to see if problem goes away.........That's certainly a possible test if I can't figure out where the problem is. I need to hook my trailer up and take it out on the highway. I can't seem to recreate it unless I'm on the gas a long time. It doesn't seem to happen without a load, I assume it doesn't take long enough to get to 70 MPH without a load behind and the problem then doesn