Losing ignition power 1999 L29

[Saab84mw]

Was driving down the expressway at 2500 RPMs running about 70 miles an hour on cruise control when the RPM gauge drops down to 1500 RPMs and jumps back up to 2500 in the process losing power to the engine like you turned the ignition switch off and back on again and it continued to do that about every minute or two.

Running with a/c off.

When I lowered it to about 2200 to 2300 RPMs running about 65 miles an hour it did it a lot less if not at all.

Any thoughts need to get this fixed so I can get a tune W/dyno done on the truck?

 

[Carlaisle]

Looking at your signature, does the engine you're asking about have 216,000 miles on it or is this a recently rebuilt engine? If rebuilt, was everything replaced or did you reuse some of the old parts? i.e. is the distributor new, sensors replaced, etc.

 

[Saab84mw]

Looking at your signature, does the engine you're asking about have 216,000 miles on it or is this a recently rebuilt engine? If rebuilt, was everything replaced or did you reuse some of the old parts? i.e. is the distributor new, sensors replaced, etc.

All new parts except for injectors and Taylor plug wires, MSD Cap, Rotor and coil only has about 7000 miles on it was replaced right before the engine went.

 

[Saab84mw]

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Here is a video from today with the issue described in the post

 

[454cid]

From the video it didn't seem like you lost any power... but you said you could feel it? The sound seemed to stay the same in the video, and your speedometer was steady.

Unless someone has a better idea, swap that MSD stuff out.... stock coil, and AC Delco or Delphi cap/rotor. I have no expereince with it, but MSD doesn't exactly have a steller reputation around here.

 

[Saab84mw]

From the video it didn't seem like you lost any power... but you said you could feel it? The sound seemed to stay the same in the video, and your speedometer was steady.

Unless someone has a better idea, swap that MSD stuff out.... stock coil, and AC Delco or Delphi cap/rotor. I have no expereince with it, but MSD doesn't exactly have a steller reputation around here.

Yes loss of power and backfiring no you can’t see it in the speedometer but you can definitely feel it in the truck.

 

[Saab84mw]

Replaced the ignition module and checked the ohms on the coil and all the wire connections found no issues that I can see.

So i tested it again setting in the driveway under no load and it is still losing ignition power and back firing.

Here is the YouTube of it.

Any thoughts would be a big help read the post contents already posted to see what I have done so far.

Thanks

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[stutaeng]

Wow, that's crazy! Doesn't seem like you have any check engine light?

Have hooked up a fuel pressure gauge?

It does seem like it could be electrical. Maybe?

This probably is going to need a scan tool with live data. Something is losing a connection or ground or signal.

 

[Saab84mw]

No check engine light started about a month ago when I was pulling my camper home from a trip, I thought it was only doing it while driving but was doing some testing yesterday and checking all the electrical connections and tried it sitting in the drive way and it is doing the same thing as on the road. Seams like it is electrical to me also.

Hot or Cold does it the same.

I was getting it ready for a Tuner and dyno runs when this started. Was thinking about going a head and getting the MPVI2+ from HP Turners (The shop for the Tune and dyno uses HP) so I thought I would go ahead and buy it so I use the data logging that come with it.

Anybody have any thoughts on the HP Tuner MPVI2+?