engine light

[3116biff]

Ok so yesterday I went for a drive up to a local ski hill, about an hour away. Went to look at some ice sculptures. Was there maybe 25mins. On the drive down I geared into 2nd as there was traffic in front of me. The road is windy and didn't want to keep using my brakes. After about 5 mins of this I though I smelled hot exhaust and my engine light came on. I would step on the gas a little and speed up and then the light would go off. I had to stop after about 20 mins to pick up my daughter. I stopped for about 5 mins. After that it is a fairly easy drive home. The light would come on and then as I would give it some gas and speed up it would go off. The truck drove fine, nothing seemed out of sorts.Once I got to town I stopped again for about 15mins. Got back in the truck and the light came back on. Today the light did not come on, but I have a very short drive to work. Could this be cuased by my cat being plugged? I am getiing a new exhaust on tues though. Any one else have this problem?

[DmaxMaverick]

Sounds like it's EGR related. Check for stored codes. The EGR can cause a strong exhaust smell and other weird things when on compression for long periods, especially at higher RPM's (like descending a hill). It does not, however, sound like a cat issue.

[3116biff]

Ok Thx . On an OBD1 is there an easy way to check for codes. My RPMS really weren't that high, not over 2000. Is there an easy way to check if the EGR is working properly?

On a different note, I had a 3 1/2 complete mandrel exhaust installed. WOW what a difference. The truck has way better pull from about 1500rpm an up. Also I don't know if its my imagination or not but the tranny seams to ship so ultra smooth. It shifted great before this.;)

[DmaxMaverick]

Checking codes on an OBD1 is simple, and requires only a paper clip and a little time. The procedure and a list of codes is HERE (http://www.thedieselpage.com/members/trblcode.htm).

Testing the EGR is simple, also. Remove it, and the components attached to it (such as the intake manifold, etc.) and set it on your workbench (or on the floor under the workbench). Observe it for a year or two (or as long as necessary to satisfy your diagnostic certainty). If it doesn't leak, it's good. In the meanwhile, if you want to drive your truck, install an F code intake until the test process is complete.

The short EGR test is not difficult, either (but requires leaving it in place). Most often, it's the EGR solenoid that's gone south. The stored codes should be revealing.

[3116biff]

Ok Thx. Diesels are new to me but I have been on here a lot trying to read up on them. Is there a big difference in the intakes?? Also you say to test it leave it on the floor for a couple yrs. I am sure you are joking with me but because I really don't know much about diesels the joke is lost on me. I am sure many will have a good laugh at this and thats ok cuz I do have a good sense of humour:p.

Also I am trying to find a good set of manuals aswell to help my virgin diesel brain.:eek:

[DaveBr]

Looking for manuals? You can get them from this sight. Go back to opening page and click on books. You will get more good info than you'll get from anywhere else.

[3116biff]

Thx I have those books already. I am talking about service manuals.:)

[DmaxMaverick]

Ok Thx. Diesels are new to me but I have been on here a lot trying to read up on them. Is there a big difference in the intakes?? Also you say to test it leave it on the floor for a couple yrs. I am sure you are joking with me but because I really don't know much about diesels the joke is lost on me. I am sure many will have a good laugh at this and thats ok cuz I do have a good sense of humour:p.

Also I am trying to find a good set of manuals aswell to help my virgin diesel brain.:eek:

No joke on you. The manifolds are essentially the same, except for the EGR. I cannot recommend you tamper with your emissions system, outside of diagnostic procedures. That would not be sound advice, and can lead to legal issues. For that reason, a little sarcasm can suggest what I might do, but can't recommend to others. I'm still "testing" many emissions system components, as we speak. No indication when those tests will be complete (I'm thorough).

For manuals and printed information, I recommend TDP prints, and the online service manual at www.alldatadiy.com. You can get full service department printed manuals at www.helminc.com ($$). I use the alldata manuals for most vehicles, if I don't have a manual in print (not many of them, any more). They are essentially the same, but alldata is dynamically updated. For print updates, you have to ask for them, then pay.

[3116biff]

Thx again. If one wanted to experiment with an F code intake is there much involved with the change over. Any computer problems? any electronics that need to be massaged? Thx aain for all the help, this site rocks.:cool:

[DmaxMaverick]

No problems switching the manifolds. As long as you leave the EGR solenoid connected. The PCM doesn't monitor the result of EGR, or the position of the EGR actuator. Just the command to actuate it, and the presence of the solenoid (it's resistance range).

Most folks just switch the manifolds (or interrupt the EGR actuator vacuum) during the test period, and leave the electrics as they were.

[JohnC]

If you switch to "F" programming, the EGR solenoid is ignored. On your '95, if you stay with the "S" programming, the PCM monitors the vacuum signal to the EGR valve, so (to keep the light off) the solenoid, vacuum pump and MAP sensor have to be connected and functional. IF it sets the code, it doesn't affect the running, but may prevent you passing inspection, depending on your state requirements. On 96 and up the MAF sensor will detect the lack of EGR flow.

[3116biff]

Ok so I have been doing some searching, I want to make sure I have this correct.

An F engine is an L65 found on heavy duty 3/4 and 1 tons. Does it matter what yrs?

Thx again for all the help. Scott:D

[Doug Thom]

I had this very problem about a week ago. Engine light would come on and then after I reached 50 to 60 MPH light would go out until I got to a lower speed. Turned out that the problem was the vacuum pump. Installed a new pump and all is well. Hope this helps!

[JohnC]

"F" is the letter that appears in the VIN if you have the L65 option, which is the 6.5 turbo Diesel installed in all 8600 and higher GVW vehicles. "S" is the L56 option in lighter chassis and "P" is L49 non-turbo (IIRC...)

[Wing Nut OOA]

i cant access the link where the code checking process is listed.

thanks- Joe

[6.5 Detroit Diesel]

3116biff- if you ever get a chance, go into action auto parts on mccurdy. they are just past the OK builders plant. they have the best selection of stuff at the lowest prices in town. lordco can't compare, trust me
they can get you some diesel manuals

[3116biff]

Ok. Im opening an old post. If I want to switch to the F code intake, do I need to switch both the upper and lower?? Is there much advantage? My engine light is coming on more frequent and I had the code red and it is the EGR. Thx for the help

[3116biff]

Anyone??????

[JohnC]

Not sure what you're asking. Changing the manifold won't make the light go out.

You cannot just change the top of the manifold. The EGR passages are in the bottom half. If you're changing the bottom, why not change the top too? Or just block off the EGR valve.

The light comes on because the MAP sensor is seeing incorrect pressure on the EGR control line. Change to L65 programming and it will never come on again.

[3116biff]

Ok Thx. Is it an easy thing to do to change to the L65 programming?

[JohnC]

Find a '95 PCM from a L65 in a junkyard or buy a performance chip.