revs to 2200 then surges between 1500 and 2000, glow plug light flashing

[rpdboss]

So i invested in a low mileage BHW salvage yard engine thinking I had a bad engine that needed replaced, Short story is it was the torque convertor bolts had backed out and tore up the aluminum guard/shim. Well swapped as mush as I could i found that i had a bad crank sensor. swapped that and it ran great without any coolant (dry test run). Later upon installing the front end i did a coolant test. No flow trough the lines, pulled thermostat (tested) and it got the coolant flowing. Now though somehow I have lost the ability to rev up to around 3200 and an reduced to 2000/2200 where alot of boost is being made and then falls rapidly to 1500 and back up to 2000 in a fast up slow fall manor. During this rise and fall in rpm the glow plug light flashes but fails to register a code. I tried pulling several sensors so its only the injectors and cam/crank ( worked before)... nope same issues.. Smoke is dark grey. on jackstands it will slowly build speed up t0 60+ but again same issues with trying to go over 2000 rpm. I dont have a vag com, only a elm327 connector. Did i bake the injectors without proper coolant flow? my fuel source is a plastic container at the tandem pump in a loop (which did get hot enough to distort and melt some...) i have another crank sensor on order. Also when i disconnect the cam sensor i get a slower start and even more limited rpm ceiling..

 

[Vince Waldon]

Your best (and fastest) bet would be to track down an actual VW-specific scanner. If the glowplug light is flashing the car has a good idea what's wrong and has set a code (or several)... just not readable over generic OBD2 unfortunately.

 

[thundershorts]

unplug the maf sensor.

 

[rpdboss]

well with the crank sensor unplugged and most other ones and after soaking in some injector cleaner... i was able to reach a black smoke 3k rpm which yes would trigger the rev limiter but no flashing glow plug light. smaller drop in rpm when it would try to go past 3k.
Yes running it on jack stands causes the traction control to get upset but I can clear and reset that system with my OBD2 chip. i have yet to try and drive it as .. well as its lacking most of the front clip besides the metal bumper and rad. No hood or headlights. I do have a dead lift pump, i have two high psi fuel pumps i can try to rig/swap with.. hey the tandem pump feeds the injectors at over 100Psi I read. As long as my other connections hold up to it. Mods are de catted and straight exhaust, no airbox, aluminum belly pan, 250K miles with a 130k engine, many plastics and bracket crap removed from under the hood.

 

[rpdboss]

Found I had a dead lift pump... Replaced it with one from a dodge grand caravan. Did some modifications and presto.. fully functioning pump and 95PSI at the fuel filter. https://photos.app.goo.gl/TPRuB1aV9JgktccX7

 

[thundershorts]

Not a good idea to use a pump not designed for the purpose. If anything, a 2.5-4 psi inline pump would be safer to use if you don't want to buy the correct pump.

 

[rpdboss]

I'm one to wonder.. it's a vane style pump with a relief spring setup. Should just bump up the pressure some and use the relief system to control the lift pumps pressure should it get you high. So far works just fine. Replaced all the hose clamps with T clamps.
Latest issue is no flow through the egr cooler and heater core. Test flowed them both with a garden hose.. no issues

 

[Tom in PT]

In post 1 you say ". . . it ran great without any coolant (dry test run). Later upon installing the front end i did a coolant test. No flow trough the lines, pulled thermostat (tested) and it got the coolant flowing." I wonder if the dry test run damaged the water pump.

 

[Mozambiquer]

I'm one to wonder.. it's a vane style pump with a relief spring setup. Should just bump up the pressure some and use the relief system to control the lift pumps pressure should it get you high. So far works just fine. Replaced all the hose clamps with T clamps.
Latest issue is no flow through the egr cooler and heater core. Test flowed them both with a garden hose.. no issues

Did you bleed the air out of the system? There's a procedure in the sticky threads on the forum.

 

[rpdboss]

Well this went badly .. so I can bleed the system.. I can get heat for a bit.. then nothing. So I slapped a electric pump after the egr before the heater core. Bleed the system and presto. Heat.. after a few mins of running... No heat and consistent stream of bubbles out the reservoir tube... So did I warp the hard when I ran it dry for a few short times or cracked block? Bad head gaskets to begin with ?

 

[Mozambiquer]

Well this went badly .. so I can bleed the system.. I can get heat for a bit.. then nothing. So I slapped a electric pump after the egr before the heater core. Bleed the system and presto. Heat.. after a few mins of running... No heat and consistent stream of bubbles out the reservoir tube... So did I warp the hard when I ran it dry for a few short times or cracked block? Bad head gaskets to begin with ?

How about the egr cooler. They are a common failure point. I got my wagon for cheap because they thought it had a head gasket blown, but it was actually the egr cooler. A couple of block off plates and it was good to go.

 

[rpdboss]

That's what I suspect too, I do have the one that was on my prior engine as a spare I'll check out

 

[rpdboss]

Update.. yes it was the egr cooler. A vacuum test confirmed that the cooler has a leak somewhere.. thus pushing the back pressure gasses into the coolant stream thus introducing a large air bubble into the heatercore

 

[Mozambiquer]

Update.. yes it was the egr cooler. A vacuum test confirmed that the cooler has a leak somewhere.. thus pushing the back pressure gasses into the coolant stream thus introducing a large air bubble into the heatercore

That would explain it! Glad it wasn't a big deal!

 

[rpdboss]

Driving it around to work out the bugs I found a faulty n75 valve, swapped it and installed new vac lines. Now I still get shudders and a seemingly invisible rev limiter between 3800 and 4200 where it shudders and cuts power. Finally got it to produce a code p0726 and traction control light stuck on.