Engine/Transmission (1998.5 - 2002) code P 1693 ?????

[Steve St.Laurent]

I think you mean the MAP sensor Gary. It senses boost pressure/manifold air pressure. A MAF sensor is a mass air flow sensor.

 

[Gary - K7GLD]

Thank you Steve - I knew it was a similar acronym, just couldn't wrap my Senior mind around it!



ANYWAY, it seems closely allied with the P-1693 codes in one way or another.

 

[jtisdale]

Is the MAF sensor also commonly refered to as the MAP (manifold absolute pressure) sensor? I am looking thru my service manuals trying to help find some causes for the P1693 code. But I need to know for sure what I am looking at.

 

[jtisdale]

Sorry, late post... dial up is great, aint it?

 

[pcarlson]

JYRO,



1693 doesn't mean anything "By Itself". It has to have another code to go with it. 1693 means a code has been set in either the PCM or ECM, our ECM automatically sets 1693 anytime another code is set.



It's a catchall code. At one point you must have had a code in your PCM/ECM and has since cleared itself but the 1693 is not self clearing.



1693 does not explain your engine running poorly. The MAP sensor has it's own code. Your problem is more than likely related to your fuel. I. E. filter change, bad lift pump, air in the system and non of these will give you a code. Get yourself a pressure gauge so you'll always be able to know your lift pump pressures.

 

[JyRO]

Latest info...

Its good to have a day off, so I can spend the day hunting for who knows what.



Here's what I've done, and what's happened.



1st thing - I disconnected both battery negative terminals. Removed the airbox, and disconnected 3 connectors on the PCM/ECM whatever - in order to clear the codes.



While removing the airbox, a check of the air filter looked way nastier than "50%" that the stock filter minder was indicating.



2nd thing - while airbox off and connectors disconnected, I ran some fuel off the fuel filter just in case there was water in the fuel and the WIF sensors didn't pick it up.



3rd thing - I used the 1-1/8th socket to tighten the fuel filter cap beyond what my fingers could do. It actually turned probably 1 to 1. 25 turns more before the torque got to the point where it felt the plastic would break. That's a lot more than I thought it would turn. Air leakage there could have been an issue.



4th - I plugged the connectors back in after well over 30 minutes being disconnected. Re-installed the airbox, and re-connected the batteries. Then I re-checked the codes - Guess what ... I still get P1693. The code didn't clear. Still that's the only code I get.



So I hopped in the truck (EZ removed last night), fired it up and backed out. It sounded OK. I gotta go about 100 yards down my road until I get out on the main road. Upon getting out on the main road when I hit 4th gear, it fell flat on its nose - absolutely no ignition (no fuel), and no check engine light. A push of the clutch and it shut off. So I sat on the side of the road only about 50 yards from my house (luckily). I sat there a while. Then I turned it to "on" and listened to the LP. The LP stayed on for about 30 seconds. When it shut off I cranked it over (sounded like it was out of fuel), it fired on the 2nd try.



So, I turned around and headed back to the house, but when I got on my road again I stopped sat there and revved it up a bit. It was running fine. So I rounded the cul-de-sac at my house and left again.



I ran that truck as hard as I dared, down to the dealer and got an air filter. It didn't mess up again. I installed the air filter and immediately could hear the turbo much better. Ran the truck as hard as I could safely down to my Cummins supplier and it never messed up again. Talked to him about it a while and ran it hard as cr@p on the way home and it ran perfect. I was pleased as to how good it ran without the EZ.



So that's what I've done today.



Gary, I thought you knew I had an EZ, sorry for not clarifying. After installing the EZ I checked the codes frequently but always got "Pnone. " I could agree that the P1693 might have taken X number of times of overboost before it would "set. " So maybe the boost elbow is purely the culprit for the code and maybe the code had set slightly before I ran into these problems. Which made the code look like it had/has something to do with this problem.



As for today's mess up. I'm going to go check the container I ran the fuel off in to see if it collected some water. Maybe the draining I did, removed some water, but enough was left in there and stirred up to give me the problem one last time just after driving off and putting a little load on the engine. I'm not sure. Maybe its that it had some residual air in there from before the tightening. I guess I'll drive it a bit more from now and see if the problems are gone.



A new air filter and maybe some drained off water seem to have helped for now. I'll keep you guys posted and thanks for the help. If what happened today sounds suspicious to you guys I'd like to hear your suspicions.



- JyRO

 

[jtisdale]

Something doesnt add up

Jyro,

Do you have a fuel pressure gauge?

I think we need to find out for sure what fuel psi you have before we can really go any farther. If you dont have one, and dont want to mount a permanent on in the cab. Get a test gauge. If nothing else, I will send you mine, as long as *I GET IT BACK*, assuming it will work with your schrader valve, and you can hook it up, tape it to your windshield and go for a good long cruise. Then, noting what you see for pressure at various throttle positions and rpm's, we can go from there.

It is possible, that you WILL hear your lift pump working, but not producing any pressure. This was the case when my pump went bad.

I was lucky enough to have an incab gauge to *watch* mine die in a matter of about 20 miles when it went. About 2 weeks before it offically died, I had noticed a 3# fluctuation in fuel pressure during normal operation. And, once in a while it would drop dramatically under any rpm's, like close to zero. All the while I could always hear the pump run before start up.

On a side note, a friend came to me last summer with a terrible miss and several puffs of smoke at about 2200 rpms. I drove the truck around awhile to note this myself. It had never quit on him, but the "stumble" was quite evident. Upon checking his lift pump, it never even ran while bumping the key, and he had less than zero (it actually drew a vacuum when we started it), but the truck still seemed to run and idle fine, with the exception of the high rpm stumble. FYI

 

[Gary - K7GLD]

JyRO - sounds most likely that the fuel filter lid wasn't secure enough, and was sucking air - cinching it down most likely corrected the actual problem - and the fuel draining probably allowed enough additional air into the system to create the temporary glitch on the first test drive - once that was cleared, yer home free!



And I agree - driving one of these later trucks - especially MODDED ones, without proper guages is like playing Russian Roulette!



Removing batteries or various plugs WON'T clear all error codes, many must be cleared by software designed by Cummins and/or DC for that purpose - and it MIGHT be that whatever deeper code that originally set your current 1693 code will have to be cleared before the 1693 will go away as well - I know *I* sure have lots to learn about codes, what sets them and what it takes to make them go away...



Computers are great - until they turn around and bite ya in the arse...



And I have the tooth marks to PROVE it! :{ :{

 

[Gary - K7GLD]

Something I shoulda included in the above - and reinforcement for the need for guages, is the fact that in a PROPERLY operating fuel system for our Cummins, there SHOULD be a POSITIVE pressure at the fuel filter canister that would not SUCK AIR in operation, but instead, leak fuel!



If, in fact, the problem this thread addresses WAS related to a loose fuel filter lid allowing air to be sucked in, that's pretty dern good evidence the LP has either failed, or isn't operating properly...

 

[machinemover]

problem solved!

Found the problem, after closer inspection one of the box fuses (30 amp ignition) was open. NOT BLOWN fuse looked good, but reads open. problem solved. HHMMM fooled by the old obvious problems once again, you'd think one would learn?

 

[Bob Cochran]

Main thing is you found the proplem.