Tranny or engine woes???

[bitsdoo]

Well folks....a new development

Just had the sending unit replaced in the truck and took it for a long drive today. I first noticed that around 60mph the engine RPM's were surging with little or no pressure to the gas pedal. It would jump about 500 RPM from just over 2000 to 2600-2700 RPM.

Over the course of the drive this manifested itself, and now when I accelerate to 60 mph the transmission runs through the lower speed with no problems but stays in 2nd (or is it 3rd) gear and when doing a steady 60mph the engine RPM's are at 3000 RPM. When I put the pedal to the floor the transmission downshifts and the RPM's jump up to about 4500 RPM, as expected. The truck should be running at just over 2000 RPM when doing this speed.

My Theory:
I've got to tell you I'm convinced the transmission is good and the engine is the cause of this. I believe that the ignition system, specifically the coil, is breaking down under load. I tested the primary and secondary resistance and the results are as follows:

Primary:
1-5 > 1.2 ohms
2-6 > 1.3 ohms
3-4 >1.2 ohms
According to the Haynes manual the resistance should be between 0.3 and 1.0 ohm

Secondary:
1-5 > 14.5 Kohms
2-6 > 14.4 Kohms
3-4 > 14.3 Kohms
According to the Haynes manual the resistance should be 6.5 Kohms to 11.5 Kohms.

Are these measured resistances out of spec enough to cause the coils to breakdown under load?

Other possibilities:

Possibly the new fuel pump is not delivering enough pressure to keep up with the demand at this load/speed?

Anybody have any ideas?

Could it be the transmission (possibly tranny or engine mounts)?

Thanks for any and all help in advance.

Cheers
Bitsdoo

 

[Glacier991]

Sounds like you do not have the 3-4 shift into OD occurring. (4th is OD). There is an electrical solenoid that controls this shift. It has a screen that can get clogged. It could be an electrical issue or possibly a valve body issue (solenoid or valve body "valve" (spool)).


You might want to view thre "My A4LD Rebuild Diary" in the useful threads forum. Covers all this. (long thread though).

 

[bitsdoo]

Thanx for the info Glacier. What you said is exactly what is happening. When doing these speeds I shifted from OD to D with no change in RPM's.

Just started reading the thread and we'll see how it goes.

Question on the solenoid. Is the 3-4 shift solenoid the one closest to the corner or is that the TCC solenoid?


Thanks again
Bitsdoo

 

[Glacier991]

The one closest to the end (with the dog ears to bolt it down) is the TCC, inner one is the 3-4.