Sputters, stops accelerating above 7psi

[dan_j_b]

My problem is that my car starts to sputter and stop accelerating above 7psi. From the data log, I see that it starts to go lean for some reason. I checked the fuel pressure and it is all normal at idle and under boost it rises properly. The spark plugs all look uniform, but slightly white. I checked all hose clamps for boost leaks. My car has been doing this for quite a while and with the nicer weather, I really need this fixed! Anyone have any ideas?


(AFR) (PSI) (rpm)
12.97 -20.7 1697
13.05 -20.6 1697
13.32 -19.6 1697
13.63 -17.6 1697
13.79 -15.4 1710
13.88 -12.9 1710
13.92 -10.3 1710
13.8 -7.7 1710
13.61 -5.2 1734
13.41 -3.5 1771
13.2 -2.8 1783
12.99 -2.3 1795
12.77 -2.2 1795
12.57 -2 1795
12.32 -1.8 1795
11.88 -1.7 1783
11.39 -1.6 1746
11.05 -1.4 1734
10.78 -1.4 1734
10.53 -1.2 1734
10.44 -1.1 1746
10.42 -1 1746
10.42 -0.9 1759
10.42 -0.8 1759
10.42 -0.7 1771
10.41 -0.5 1771
10.39 -0.5 1771
10.38 -0.4 1771
10.38 -0.2 1783
10.36 -0.1 1783
10.35 0.1 1795
10.35 0.1 1795
10.33 0.2 1807
10.33 0.3 1807
10.33 0.4 1820
10.32 0.5 1820
10.32 0.5 1832
10.3 0.6 1832
10.3 0.7 1844
10.3 0.8 1844
10.3 0.8 1869
10.32 0.9 1917
10.32 1 1942
10.32 1 1954
10.32 1.1 1954
10.35 1.2 1966
10.39 1.3 1966
10.42 1.4 1978
10.47 1.5 1978
10.5 1.6 1991
10.53 1.7 1991
10.57 1.8 2003
10.61 1.9 2015
10.64 2 2015
10.69 2.1 2027
10.73 2.2 2027
10.78 2.3 2040
10.82 2.4 2040
10.83 2.5 2052
10.86 2.6 2064
10.86 2.6 2064
10.88 2.7 2076
10.89 2.8 2076
10.89 2.9 2088
10.89 3 2101
10.88 3.1 2101
10.88 3.2 2113
10.85 3.3 2113
10.83 3.4 2125
10.82 3.5 2137
10.82 3.6 2137
10.8 3.7 2150
10.79 3.9 2162
10.78 4 2162
10.76 4.2 2174
10.75 4.3 2174
10.73 4.4 2186
10.73 4.6 2186
10.73 4.8 2198
10.73 5 2211
10.73 5.1 2211
10.73 5.3 2223
10.73 5.5 2223
10.72 5.6 2235
10.72 5.8 2247
10.7 6 2247
10.7 6.2 2260
10.7 6.4 2260
10.69 6.5 2272
10.69 6.7 2272
10.67 6.9 2284
10.69 7.2 2284
10.76 7.3 2296
10.82 7.6 2296
10.91 7.8 2308
10.98 8 2308
11.07 8.1 2321
11.14 8.3 2333
11.22 8.3 2333
11.29 8.4 2345
11.35 8.4 2357
11.42 8.5 2370
11.45 8.5 2382
11.5 8.5 2382
11.55 8.6 2394
11.55 8.6 2406
11.55 8.5 2406
11.55 8 2406
11.51 7.7 2406
11.36 7.8 2406
11.25 6.9 2418
11.25 4.9 2418
11.45 3 2418
11.67 1.2 2394
11.76 -1.1 2345
11.8 -5.6 2321
11.83 -10.9 2333
11.82 -14.4 2333
11.77 -16.1 2333
11.73 -17.9 2321
11.67 -19.7 2321
11.66 -20.8 2321
11.76 -21.2 2308
11.83 -21.5 2308
11.82 -21.5 2296
11.6 -21.7 2296
11.39 -21.7 2284
11.29 -21.8 2260
11.29 -21.9 2198
11.27 -21.9 2162
11.29 -21.9 2162
11.33 -22 2150
11.39 -22 2150
11.44 -22 2150

11.86 -21.9 2064
11.89 -21.9 2064
11.91 -21.9 2064
11.92 -21.9 2052
11.94 -21.9 2052
11.92 -21.9 2052
11.91 -21.9 2040
11.91 -21.8 2040
11.92 -19.6 2040
11.94 -15.2 2027
11.97 -12.9 2027
12.01 -12.5 2027
12.1 -12.1 2015
12.25 -11.5 2015
12.44 -10.7 2015
12.66 -11.9 2015
12.91 -14.6 2015
13.14 -14.6 2015
13.39 -12.6 2015
13.63 -10.7 2015
13.85 -8.9 2015
14.05 -7.3 2015
14.23 -5.6 2040
14.44 -4.4 2088
14.64 -3.8 2113
14.71 -3.2 2113
14.63 -2.7 2113
14.44 -2.2 2113
14.2 -1.7 2113
13.91 -1.4 2125
13.66 -1.1 2125
13.39 -0.9 2125
13.13 -0.6 2125
12.86 -0.4 2125
12.61 -0.1 2137
12.36 0.1 2137
12.1 0.3 2150
11.8 0.5 2150
11.58 0.7 2150
11.48 0.9 2162
11.41 1 2162
11.38 1.2 2162
11.32 1.4 2174
11.29 1.6 2174
11.23 1.8 2186
11.2 2 2186
11.17 2.2 2198
11.14 2.5 2198
11.11 2.6 2198
11.08 2.9 2211
11.05 3.1 2211
11.02 3.3 2223
11 3.5 2223
10.97 3.8 2235
10.95 4.1 2235
10.92 4.3 2247
10.91 4.5 2260
10.89 4.7 2260
10.88 4.9 2272
10.85 5 2272
10.83 5.2 2284
10.82 5.3 2284
10.8 5.6 2296
10.79 5.9 2308
10.78 6.1 2308
10.78 6.4 2321
10.76 6.6 2333
10.76 6.9 2333
10.75 7.1 2345
10.78 7.3 2357
10.85 7.6 2357
10.92 7.9 2370
11 8.1 2370
11.07 8.4 2370
11.13 8.7 2382
11.19 8.9 2382
11.14 9 2382
11.16 9.1 2394
11.29 8.3 2394
11.73 6.8 2394
12.23 4.6 2394
12.45 1.9 2394
12.49 -1.7 2394
12.47 -6.9 2394
12.42 -12.1 2394
12.36 -16.1 2394
12.3 -18.6 2382
12.26 -20.1 2382

[vntshadow]

check your intermediate shaft gear/oil pump gear mesh. Remove distibutor and look thru hole and inspect gears. May help to rotate motor to inspect whole gear.

[dan_j_b]

the problem is specific to when it's boosting. if I keep the boost down, it revs all the way up and down fine.

[1966 dart wagon]

are you getting any codes?

[shackwrrr]

are you getting any knock retard? It could be pulling all your timing and it falls on its face

[vntshadow]

If you have a problem with the intermediate shaft, it will also pull timing, making it sputter and backfire when your in boost. When it(shaft) gets worse. it'll even intake backfire.
I only recommend looking at the gear mesh and see if it is worn.
When mine went bad, you could see the whole entire face of the teeth down to bare metal. Only on 1 side of each gear. Which is why to turn(wrench)motor and inspect. Good gear mesh should be right in the middle of the face
of each tooth of gears.
This would of saved me alot of time, money and aggravation, if I would have been told sooner.
Good luck w/ diagnosis.

[dan_j_b]

The CEL hasn't come on, but then again, it never comes on when I turn on the key or anything so thats another story. I'll pull the distributor and check the gears there once I get ahold of a timing light. I am pretty sure there are ways to log retard and knock so I'll check into that as well. Also Ben mentioned that it could be caused by a bad connection in the injector harness or lack of proper ground.

[dan_j_b]

I logged some more and according to it, the knock sensor volts are around 6.5-7V when its under boost and cuts out. The max retard shows .41V if anyone knows the conversion to degrees.

[dan_j_b]

According to what Shelgame said, since the raw data (0-255) output showed 21, this would translate to 10.5 degrees.

[cordes]

According to what Shelgame said, since the raw data (0-255) output showed 21, this would translate to 10.5 degrees.

That's how much timing it's pulling due to knock? If so you need to back off the timing big time. Yikes.

[dan_j_b]

Yeah I'm not sure if thats 100% accurate, but I will check the timing for sure

[dan_j_b]

Well I checked the timing, it was around 11 so I set it at 12, not a problem. I looked at the gear in there behind the distributor and it looks ok. I redid the ground from the intake to the body and from the body to the battery with 10 gauge and bolts isstead of those darn self-tappers, no improvement. I noticed some oil on the surfaces inside the HEP and distributor so I cleaned the HEP and replaced the cap and rotor. After I did this, it actually boosted all the way up to 20 psi once or twice, then after that it was back to the old problem. Then to make matters worse, I was trying to merge on the interstate and boosted high enough where it was cutting out and I heard a loud pop, something metal falling off, lost boost, vacuum (brake booster) and the engine got really loud like the exhaust fell off. Turns out the large expansion plug on the end of the intake popped out. I don't know if this happened as a result of the other problems I've been having or if it was just not in there good enough. I even used anerobic gasket maker on it back when I replaced it.

[shackwrrr]

sounds like a bad lean pop. Howabout your fuel pressure since your timing is set fine but the computer is still pulling timing.

Or the Ref side of the Hep is going bad and its not injecting fuel when it needs to.

[dan_j_b]

I checked the fuel pressure and it is normal at idle and under boost it rises properly.

[shackwrrr]

Find yourself a known good hep and swap it out.

[dan_j_b]

This is weird, I was driving home last night in the dark and noticed this: When I accelerate and it goes past 4psi, all the lights dim for a second. Could this be a problem with the MAP? I can't think of anything else that links boost with the electronics. I don't know if this has anything to do with my problem, just thought it was odd.

[cordes]

This is weird, I was driving home last night in the dark and noticed this: When I accelerate and it goes past 4psi, all the lights dim for a second. Could this be a problem with the MAP? I can't think of anything else that links boost with the electronics. I don't know if this has anything to do with my problem, just thought it was odd.

Fan kicking on when reaching a certain boost threshold?

[dan_j_b]

Yeah I bet thats it. In D-Cal, the FanBat table controls that and I see that I have it turned on.

[dan_j_b]

I checked my turbo, and it has a LOT of side to side endplay and some in and out so I have sent it in to be rebuilt at TU. I will let you know if that fixes everything

[minigts]

Just to confirm, you are pulling the coolant temp sensor plug when checking timing, correct? It has to be asked.