1997 D1 Issues are back, no codes and no CEL

mrbieler

Well-known member
Sep 15, 2004
71
13
Lost Angeles
At the end of 2018 and into January 2019, I post this thread about our 97 D1


Since January 2019 after the work done to fix the above issues, the truck has been flawless. It was driven a lot this summer by my son when he was home from college. It sat from late August until a couple of weeks ago. I'd take it out once or twice to keep things happy, but just local runs. Last week I ran it around for some errands, check fluids, etc and generally got it ready for his return home for winter break. Ran great. No issues. Picked him up at the airport in it on Sunday.

Yesterday, on the freeway, it lost power started to sputter and backfire. Wouldn't get above 1000 RPM regardless of throttle position. Limped home at about 9MPH. Engine was gutless. Sat overnight and the morning fired up strong. Checked wires, plugs, and fuel pressure. All looked good. Drove it around the local streets for about 10 minutes and then wanted to give it a one exit run on the freeway to see what was going on. 500 yards on the freeway and the issue returned. Limped back home. Truck sat for most of the day. Now fires up strong again.

The issues this time are little different. No wandering idle. No black sooty exhaust. Just a sudden gutless response any throttle position when warm and it will sputter and backfire if held at rpm (1000 the highest it will go). As before, no codes and no CEL to guide me.
 

Toran

Well-known member
Feb 3, 2017
416
48
Ohio
I am no very curious about this issue with your truck. You have posted in great detail so I am simply reading and re-reading it.

Do you know if you have any stuck fuel injectors?
What about the fuel regulator?
Fuel pressure when truck is running?
 

mrbieler

Well-known member
Sep 15, 2004
71
13
Lost Angeles
Will check the CPS and wiring. I always thought it was an all or nothing sensor. Bad signal meant no ignition. I was able to limp the 1 1/2 miles home at about 9MPH and a very unhappy truck.

Truck is stock. Fuel pressure when I check when it's cool before it starts acting up is fine. 38 at ignition, about 31 when running, and about 29 under load. I have not checked while it's running rough. MPG is same as it's always been for the last 19 years, about 12MPG.

As I mentioned above, when it's cold, and just a this past Monday, it drove great. Lots of power. Running smooth. Does make sense that it's wiring related as something is clearly unhappy when it gets hot. Just wish something would flash on my OBD Fusion to clue me in. Shows all is well and tells I'm ready for my smog check in the spring...
 

mrbieler

Well-known member
Sep 15, 2004
71
13
Lost Angeles
CPS is bad and replaced. I decided to get shop help as I'm having shoulder issues and couldn't get the work done. They pulled and cleaned the CPS. Nope. Swapped out the ECU. No help. Checked the cats for blockage. No issues. Installed new CPS. Good to go.

My long standing mystery coolant loss looks to be the rear of the heads. Appears to have pooled on and killed the CPS over time.

Now need to start thinking about top end work and a head gasket replacement. Truck is running the originals so they've done their job.
 

joneschris

Well-known member
Aug 25, 2019
167
32
The Woodlands, TX
CPS is bad and replaced. I decided to get shop help as I'm having shoulder issues and couldn't get the work done. They pulled and cleaned the CPS. Nope. Swapped out the ECU. No help. Checked the cats for blockage. No issues. Installed new CPS. Good to go.

My long standing mystery coolant loss looks to be the rear of the heads. Appears to have pooled on and killed the CPS over time.

Now need to start thinking about top end work and a head gasket replacement. Truck is running the originals so they've done their job.

Did you check the wiring?? As Will mentioned above. I had this exact same problem, and it was the wire, not the sensor
 

robbyb20

Well-known member
Oct 2, 2019
227
34
Seattle
Did you check the wiring?? As Will mentioned above. I had this exact same problem, and it was the wire, not the sensor
I could be mistaken but it looks like a new CPS fixed their issue since they are "Good to go" and now working on their gasket issue.
 

dos531

Active member
Feb 1, 2016
27
7
Rowland Heights, CA
As others said before, check the wiring to the cps. I bought mine barely running and the previous owner couldnt figure it out. Tracked it down to bad insulation on the cps so the wires were touching. Fixed it and never had an issue since. Also only cost a few cents in insulation and wire to fix!
 

mrbieler

Well-known member
Sep 15, 2004
71
13
Lost Angeles
A new CPS resolved the issue. Old CPS was coated in coolant and gunk. The wiring harness checked out OK. Moving ahead with head gasket replacement. The old coolant loss I've been accepting for years has gotten a fair bit worse. Truck turned 24 this month. It deserves the attention.