Engine/Transmission (1998.5 - 2002) Engine returns to idle speed

[sp_longhorn]

Hey guys I really could use some help with this one, I have tried everything I know to do. Here it is 2001 5 speed driving down the road, don't matter what gear, you will being going alone fine then all of sudden the engine goes back to idle speed. Just like if you had the cruise on and just tapped your brakes to turn it off. The engine will gradly build the rpms back up and then do it again. It's not happening at any particular rpm or speed. Check engine light comes on and show a code of 1693. Now what has been done to this truck is a new injector pump and a apps. After installing the injector pump it did not do it for quite some time now it's back to the same problem. No change at all after a new apps. Any and all help will be greatly appreciated.

 

[SpicyJam]

Your truck is in limp mode. The has been a failure with the computer talking to the VP44, and yep that does mean you will need another pump. This just happend to a friend of mine a couple of weeks ago. Sorry dude



Hold up here, I am sorry after reading what was going on with your truck, for the thrid time, sounds more like a MAP sensor. We had a '99 in the shop that did just the same thing. You have a scanner or access to one? I know with the truck we had the boost was at 49psi at idle... ... ... ... . lol. I would bet that this would be your problem. They are around 50 bucks from Cummins.

 

[mmi]

MAP might be a good start.

You will need someone to read the codes. And check all the pollution gadges.

We have had this several times. More frequent on gas eng.

 

[sp_longhorn]

Thanks guys for the feedback, I put a new map sensor in last night and got the check engine light off. Reconnected batteries fired her up and headed down the road, less than 100yds same thing falls right back to an idle... Do I need to just get the codes scanned, maybe that will tell something different. The way it stands right now is a code 1693. .

 

[SpicyJam]

You will need to have the codes cleared, then see if it will set a new code, once you fire it back up. If you were closer I would gladly lend ya a hand, but someone in your area must have a scan tool.

 

[Mundgyver]

If the map sensor fixed the problem, the light will disapear after 3 clean starts and the code will clear from the system after 40 consecutive starts with no reoccurance of the error condition. I seem to recall this being in the manual. I don't have it infront of me at the moment, but can verify tonight when I get home. This is one of the reasons I bought a Roadrelay, diagnostics are straight forward and clear.

 

[sp_longhorn]

Ok guys this is what I have thus far, I got the codes pulled and it read a 1689 and 1693. Any thoughts??????

 

[Mundgyver]

Ok guys this is what I have thus far, I got the codes pulled and it read a 1689 and 1693. Any thoughts??????



Page 25-16 in the 2001 service manual.



Code 1689 = No communication between ECM and Injection Pump Module. Data link circuit failure between ECM and fuel injection pump. Low power, engine derated, or engine stops.



Code 1693 = 1st part = DTC Detected in Companion Module. A fault has been generated in the companion engine control module.



2nd part = DTC Detected in PCM/ECM or DTC Detected in ECM. A"Companion DTC" was set in both the ECM and PCM.





:{ This does not look good for you.

 

[sp_longhorn]

What does this really suppose to mean, I read somewhere about a 1689 code refering to a oil pressure sensor. My oil pressure reads fine though.

 

[SpicyJam]

OK with them codes, back to what I first thought, the VP is junk. Your truck is in limp mode. I saw you had just put one in, I just hope you got the right REV for your truck. Other than that if you ever need to find out what codes are what go to the forum "911" and there is a sticky listing most all the codes. good luck... ... ... .....

 

[Sputnick]

Me Too!

I have one doing the same thing, im trying the conectors to see if they are wet or making a bad connection. could also have a broken wire. ill post if i luck out and get it fixed.

 

[RCrawford]

My truck did the some thing. I unded up replacing the Throtle Position Sensor. Hasn't happened sense. Only problem is, this sensor is around 450. 00 dollars. Simple to install thow.

 

[sp_longhorn]

I believe we have fixed the problem. It seems someone has been into the wiring harness before going to the injector pump. The data wires had been into before, but the shielding was not installed back onto the wires to stop interference. Appartlenty the engine at certain times was inducing noise onto the data wires, making loss of communications to the ecm. Thanks for all the replies guys.