P8037 - P8038

[CBari]

My 2003 has a weird issue where running at low speed after a cold start the engine acts like it just cuts out for a split second. Doesn't seem to do it once it get to speed of 45 or more, nor does it do it when it warms up to operating temp. When I do the key cycle to look for codes the P8037 & P8038 show up and I can't find any think on those codes.

 

[Darkbloodmon]

Strange..... Have you tried doing a hard reset? Disconnecting both battery cables and holding a negative and positive cable together for a bit then reattaching them and checking for codes? That or using a scan tool to erase those codes and try reading again. I'm getting duds in my search for those codes as well.


Have you changed anything recently on your truck? Tuned?

How many miles and what transmission?

What kind of climate do you live in? Could be a fuel pressure related issue.

 

[CBari]

Strange..... Have you tried doing a hard reset? Disconnecting both battery cables and holding a negative and positive cable together for a bit then reattaching them and checking for codes? That or using a scan tool to erase those codes and try reading again. I'm getting duds in my search for those codes as well.


Have you changed anything recently on your truck? Tuned?

How many miles and what transmission?

What kind of climate do you live in? Could be a fuel pressure related issue.

I'll try the hard reset, I have cleared the codes with my scan tool only to have them return never have had a check engine light with these codes either.

Engine is the 305HO, Trans is the 48re built by Groend 175k miles ago. Truck has 290k miles on it. Have had a smarty on it for 200k miles, only real electrical problem I have had is the rpm on the dash has been off for years.

Nothing changed on the truck in last 5 years only put maybe 5 - 7500 miles a year on it since it got relegated to a farm truck.

 

[Ozymandias]

The scantool gives the same weird codes as the tach?

 

[CBari]

The scantool gives the same weird codes as the tach?

Yes

 

[Darkbloodmon]

How is it on initial start up hot or cold? Does it struggle or skip?

Is your fuel system factory spec or aftermarket? Can you get fuel pressure readouts?

 

[CBari]

How is it on initial start up hot or cold? Does it struggle or skip?

Is your fuel system factory spec or aftermarket? Can you get fuel pressure readouts?

It will sit and idle hot or cold with no skip. Fuel system is factory still with the factory filter mounted lift pump, I have changed multiple times over the years. Unfortunately I don't have way to get pressure readouts.

 

[Ozymandias]

Before even think about throwing parts at it, go to a dealer that still has a DRB III around to diagnos it.
These codes are so weird it could be a faulty ECM that generates it, same as with the slight cut outs, or say stumble, of the engine.

I have a hard time that the fuel supply would give single cut-outs, especially because that engine runs without a lift pump as soon as it runs.

 

[CBari]

I had another thought over the weekend while driving the truck back in the summer the AC was acting up and it ended up being the fan clutch causing the problem, I have since learned about the issues with the non-OEM fan clutches and wonder if this could be my issue. The cutting out seems to be much worse when the AC is on and the fan clutch is locked. While it is still present with the AC off it is far less often and noticeable. Wondering if I can just unplug the fan clutch and run it and see if the problem disappears.

 

[Ozymandias]

You can, will give you a single CEL code for that.

 

[CBari]

You can, will give you a single CEL code for that.

Well I am back in town and been driving the truck for the last few days and last night it was terrible cutting out, while cruising around 60 down the highway without the cruise. When I used the cruise it was there but way less noticible, more surge like. I still had the theory that it was tied to the fan clutch and while I felt it this bad before I usually had the A/C on when it was this bad. So this leads me to a lock up question. Heat was set to the floor vents, fan on low does this setting call for lock up? Engine temp right around 180. This morning before leaving in the truck I unplugged the fan clutch and on mile 10 mile commute, no issues. I think I am on the right track I will try to drive it a while like this.

 

[Ozymandias]

I've driven mine for three weeks without the fan till was able to change it. No problems, as long as you don't tow a trailer the engine stays cool easy.

 

[CBari]

Well figured an update was due. First off I must have a touch of dyslexia as the codes are P0836 and P0837, these both point to the mux switch on the 4wd. It is a 5v switch so maybe it is what has been causing the weird miss or cutting out issue. I have a switch and will get it put in when I have time. The theory on the fan clutch got shot to pieces when problem occurred with the clutch unplugged. The switch issue showed to have been there for 255 key cycles which is the max the computer stores so it has been around for awhile.