Do you not have a boost regulator? That overboost condition will cause your truck to defuel big time.

 

My experience with adjusting my special spring to limit boost to 20-22 psi Click for full size image , is that the wastegate only has to just barely crack off its seat to limit boost to this level, and that's using my 70 hp chip. Since the extra force of the zip tie helped, maybe your wastegate isn't making a good seal?

 

I think this could be a big part of the problem. You will get no codes if the PCM never sees excessive boost. Likewise, the PCM will not provide enough fuel if the map sensor does not see enough psi to call for it. I would disable this and see if I could get some smoke and a defuel situation which would then throw a code. Just a thought, I'm not sure of the design and plumbing of that regulator.

 

Well I think there is something going on electrically. I replaced the Map sensor and the lines going to the Map, removed the pressure regulator, and put real hose clamps on it. My Boost gage reading is t'd into that line. When at an idle my AE registers around -2 psi on the map. At 5psi on the boost gage, Map registers .5 then stays about 5 psi behind in a linear fashion up to a max of 13. When towing some hills yesterday it was absolutely pathetic. No torque at all, and no boost. At one point I was 1200 egt, 26mph, 2nd gear, and 7psi according to the boost gage. That would have put the Map at about 2 according to the AE. The low boost problem is something that I have had for about 2 years(and 3 motors), but was never bad enough to be a huge problem. Although in retrospect, maybe that led to the early demise of my last 2 engines? Anyhow, what are some electrical checks I can do to test the MAP? and where is the Baro sensor at? What else is there that is not on the motor that could have such an impact on boost and performance?

After towing I had the following codes as well
P1247- turbo boost pressure low
p1248- Turbo boost pressure not detected
p0238- Turbo boost sensor A circuit high

Ugh this is getting maddening. We are heading out today for a weeklong camping trip, but may make it to town to check up for any additional info. Thanks for all the Help!!

 

You have the air compressor regulator in the MAP line, but what do you have it set at, as far as how much PSI can the MAP Sensor see? The Turbo boost pressure Low makes me think that no pressure is getting to the sensor, OR you have a BAD MAP sensor. EDIT- upon looking at my wiring diagram and seeing that you have a MAP Pressure not detected, and "Circuit High" means that the 5v Vref signal is sent out and 5v comes back, there is no resistance in the sensor which throws the code.

 

I removed the Air pressure regulator from the Map line. I am trying to get back to a baseline to start from. ANd I replaced the Map sensor and still have the same readings as before. I checked referance voltage at the map using a VOM, and have 5.02. My wastegate control DC never changes from 99.11. Another item of note was that while towing, no matter what power setting, I never got an overboost condition, with the map hooked up in OEM fashion and the Wastegate line removed.

$10,000 on a motor and 4.56 gears I can now tow hills at less than half the speed I could with a stock motor and 3.73 . Bet it is all caused by a missed connection or some $5 part.

 

Check fuse #30, 30a, in the junction box/ fuse relay panel. Also, on the same circuit is the fuel heater, on the bottom of the fuel filter bowl. Are you sure that it is not burned out? Or, even, plugged in?

 

Does your boost gauge match what AE is reading for Manifold Gauge Pressure?

Also at KOEO does BARO match MAP within 1psi, and does BARO match Ambient pressure (Convert weather channel mmHg to psi)

Couple of other comparisons to check on cold engine (sit overnight) is EOT and IAT and MAT. PCM uses MAT to adjust fuel timing.

 

Alan- Checked IAT and MAT temps this morning and they were within a few degrees, EOT was 61, IAT was 57. Did not check the MAT. Baro and Map were about 2.5psi off of each other. One was 11.2 the other was 13.7.

I decided to back up and follow the obvious symptom being the WGS being stuck at 99.11 using your AE sheet as a guide. Resistance between 1 &2 on the solenoid was 47ohms. Voltage on connector pin 2 was 12.2(KOEO), however, resistance from connector pin 1 to ground was only 203 ohms. I unplugged C138 and checked from there, still 192 ohms. Unplugged PCM and it was and same wire was an open. plugged 138 back in and still had an open from pin1 on the WGS connector. Plugged PCMback in and had 203ohms again. A little bit off from the >10k you specify. Is it worth the cost of trying a new PCM?

And my boost gage is consistantly about 5 psi above the AE manifold gage pressure.

 

That 10K came straight from the factory service manual. Here is the resolution if < than 10K "REPAIR short to ground on Circuit 1275 (W/R). RESTORE vehicle. CLEAR DTCs and RETEST"

Where is your boost gauge tapped? I am seeing a 5psi leak somewhere between the MAP and Boost tap.unless this is an issue with your chip (some programmers fool with the MAP Tables)

 

I just got off the phone with Banks (have bighead wastegate) and they are thinking that the low boost problem could be from a MAP sensor problem. My truck would only make 12 lbs of boost under a heavy load and last weekend hauling I only got 5 lbs on hills at best!!!! Banks told me to check the hose that runs off the sensor for cracks.

 

Jason:

Not to hijack... I know that you're very busy....just FYI...

I sent you my Cackle-cure evaluation report by email. Disregard the one from last night. The one sent this morning is the one to look at (when you have a few "spare" minutes). If it hasn't shown up yet, let me know and I'll send it again via my work email.

 

ok well I am in the desert with no phone service to speak of, but have digital service. go figure. so much typing this on the phoone. I continued doing t/s on my map. koeo baro reads 12.8 psi, ebp reads 12.4, and map reads 11.1. both the old and new map sensors read that. manifold gage pr. reads 0.0. still with koeo, I connected my map to my little air compressor set at 25 and the map reads 17.4. my boost gage also registers 25. map wires ohm out fine to pcm. 12.8 is consistant with my elevation. do I have a bad pcm not reading the map right? also, what is normal for ebp at say 15psi boost? thanks for the help

 

With a 5" exhaust i am in the low 30's at 15# boost, if I remember correctly stock I was around 42-45.

Check with your chip/tuner maker and see if he is playing with the MAP tables. Or you can try to get a voltage reading from the MAP
Volts kPa PSIA
1.1 80 11.5
1.5 101 14.7
2.2 138 20
2.8 172 25
3.6 206 30
4.3 242 35

 

Alan and everyone thank you for your help. not sure why it never occurred to me, but when I removed the chip it doesn't run well but all readings are normal again. I finally drove 120 miles round trip to the nearest hardware store and got the stuff to pressurize the intake and sure enough my orange boots on the intake were leaking. So I tightened those to the point I thought the clamps would strip and gained 7-10 psi at wot. Saturday I will see how towing does.