Fixed knock issue with new MAF, now I have a fuel issue?

[ScottHeidinger]

You can reset the ECM now or later. Seems like you're chasing fuel. My guess is that the rail gauge is not correct and the rail doesn't have enough fuel pressure since it ran good showing much higher pressure but if the pump isn't producing enough volume at that pressure it could be a pump issue. The gauge you can read inside the car should help you see if the rail pressure rises with boost


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[krisking94]

I'm thinking maybe before I reset pcm I should purchase a new FP regulator and gauge. If I reset the pcm now and that still did not fix the issue then I may not be able to get the car to run along to finish the drive cycle after a pcm has been reset. I feel like I would really be in the dark then because the car would be stuck at trying to re learn everything but it can't stay running

 

[krisking94]

You can reset the ECM now or later. Seems like you're chasing fuel. My guess is that the rail gauge is not correct and the rail doesn't have enough fuel pressure since it ran good showing much higher pressure but if the pump isn't producing enough volume at that pressure it could be a pump issue. The gauge you can read inside the car should help you see if the rail pressure rises with boost


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After work I will go to autzone get the gauge and vac line combo you mentioned. Then I will take my FP gauge at the rail of my t type that I know works. I'll let you know how it goes. Thank you!

 

[earlbrown]

I just skimmed this post but your first line mentioned replacing the MAF....



..if you replaced it with a stock replacement from a parts store, there's about a 5% chance you got a good one. Stock MAFs are crap and stock replacements are even worse.


Trying to tune around one is an exercise in futility.


If you have a Translator and LT1/LS1 then ignore the above.

 

[Chuck Leeper]

5 yrs on a fuel filter..5 yrs on a pump & sock?
Scott mentioned the inaccurate rail gauges. I've checked many, on my inj bench....Junk.

 

[krisking94]

5 yrs on a fuel filter..5 yrs on a pump & sock?
Scott mentioned the inaccurate rail gauges. I've checked many, on my inj bench....Junk.

Okay so here's where I'm at. Finally got the new FP regulator in the mail. Put it on this morning. Car fired right up. I set FP to 45 line off. Unplugged orange battery cable to reset pcm. Did the drive cycle. Car is now getting knock again in boost like it was before everything happened. Car runs and drives great if your just cruising around town, so I assume regulator was apart of my issue. I wonder though if my Fuel pump is not strong enough to handle 43-45 static FP. When I initially swapped MAFS I could fully get into the boost without getting knock, but my FP was almost 60psi with the line off. Turned it down to 43 then I got knock. Turned it back up then no knock. Then the next morning car wouldn't start. Replaced filter. It ran for a bit, could still get into full boost with no knock. Then the car wouldn't stay running after that and the Reg was reading very inconsistent. Replaced reg, car runs and drives great under normal conditions but is having knock again. I did a little test and at 43 psi of FP with the line on (about 51 static) I got 4.6 degrees of knock and my 02 readings were at 805. So not necessarily leaning out but I was only at about 10-12 lbs of boost. I drove it for a couple hours total today. After I got home and put it park I recorded some SM numbers and here's what I got
761mv
Af-04
L8-33
Bat- 13.9
Int- 128
Bl- 133
Clt -179
Ats-104
Rpm- 700-750
Tps- .44
Iac - 30

Should I try to put the other maf back in and see what it does or should I not even bother because when I intailly swapped mafs and had super high FP I was having no knock. Maybe my fuel pump is not proving enough volume at 43psi of fuel. I have a new fuel pump for the car but have not put it in yet.

 

[krisking94]

You can reset the ECM now or later. Seems like you're chasing fuel. My guess is that the rail gauge is not correct and the rail doesn't have enough fuel pressure since it ran good showing much higher pressure but if the pump isn't producing enough volume at that pressure it could be a pump issue. The gauge you can read inside the car should help you see if the rail pressure rises with boost

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I got the regulator in. Car runs and drives great under normal conditions. But I'm back to square one with getting knock at low boost. Same issue I had before I put new maf and lowered FP back down to recommend psi.

 

[Pronto]

You need to monitor the fp at boost. The pump may be making enough pressure for normal driving but unable to keep up with high demand volume wise. You shouldn't need to run the rail pressure that high. You need pressure guage on a long line that you can tape to the windshield.

 

[ScottHeidinger]

You need to monitor the fp at boost. The pump may be making enough pressure for normal driving but unable to keep up with high demand volume wise. You shouldn't need to run the rail pressure that high. You need pressure guage on a long line that you can tape to the windshield.

X2


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[Gene Van Horn]

I hated that i had spend 200.00 for a fuel pressure gauge. I got mine because if 100 people tell you something is white, what color is it. There are a couple venders sell fuel pressure kits that skrew to the under side of hood so you can see when driving. Yes its kinda exspensive, yes its kinda ugly sitting there all the time rite in front of you. No i would not be without it now that ive gotten used to it, go into boost pressure rise one to one rite in front of you. Believe the guys when they tell you how important it is to moniter that pressure when into boost,they know what they are talking about and as most have found out at one time or another what happens when it doesnt. You can borrow one to check it and it sounds like yours isnt rising, ie not enough pressure under boost but i would buy a permanant one if i were you.

 

[krisking94]

You need to monitor the fp at boost. The pump may be making enough pressure for normal driving but unable to keep up with high demand volume wise. You shouldn't need to run the rail pressure that high. You need pressure guage on a long line that you can tape to the windshield.

X2


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on a side note how do I tell the pcm was reset correctly and the car went into open loop idle? Just wanna make sure that it did actually switch over after I did the drive cycle

 

[ScottHeidinger]

If you unplug the battery cable for a minute it will reset it every time. I often don't want it to happen but it does.


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[ScottHeidinger]

I drove around in a t-type back in the 90's running no real gauges and had that car spitting, sputtering and bucking because I had no clue what I was doing. No scan master just a heavy right foot. It's amazing that car stayed together but now I feel naked without water temp, oil pressure, fuel pressure, knock sensor, boost gauge and a power logger screen.


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[TurboTGuy]

I drove around in a t-type back in the 90's running no real gauges and had that car spitting, sputtering and bucking because I had no clue what I was doing. No scan master just a heavy right foot. It's amazing that car stayed together but now I feel naked without water temp, oil pressure, fuel pressure, knock sensor, boost gauge and a power logger screen.


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Please keep ALL the gauges..... None of us wants to see the counterpart of the equation........

 

[krisking94]

O

If you unplug the battery cable for a minute it will reset it every time. I often don't want it to happen but it does.


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Oh yea I know when you unplug the cable it'll reset everything. I unplugged it. Drove it around for 15 minutes like the instructions state. But how do I know the car actually went into open loop idle compared to closed loop

 

[626gn]

O

Oh yea I know when you unplug the cable it'll reset everything. I unplugged it. Drove it around for 15 minutes like the instructions state. But how do I know the car actually went into open loop idle compared to closed loop

Decimal blinks in open loop.

 

[krisking94]

If you unplug the battery cable for a minute it will reset it every time. I often don't want it to happen but it does.


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UPDATE** okay I just got done installing my DW300 fuel pump. Car stays running and driving now, but still getting knock at boost. So far since I first replaced the maf and it had no knock ( before I turned FP down from almost 60 static to 43-45 static). Since swapping mafs I have replaced the regulator with another kirban one, ac delco fuel filter and now the Deatswerck300 fuel pump.
Here's what my scanmaster readings are now after I just took it for a cruise after fuel pump install ( no leaks have triple checked).
02 - 500mv (seems very low)
Af-04
L8-32
bat-13.8
Int-128
Bl-135
Clt-178
Ats-106
Rpm-700-750
Tps-.44
Iac- 34 (little high)
Cc - is jumping up in incriminates of about 40-50 each time until it resets (is that an indication of faulty 02 sensors)

 

[ScottHeidinger]

Cc jumping shows its functioning it should do that.


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[krisking94]

Cc jumping shows its functioning it should do that.


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Well then what else do you think could be my issue? I'm just very confused. When I had just initially swapped mafs and fuel pressure was still up very high it was not knocking. Then I went to go turn down fuel pressure to 43 static it started knocking. Turned it back up, no knock. Then the next day all the issue started. After I had replaced the regulator I did reset the pcm. I feel like though the car should be sophisticated enough to relearn on its own without having to reset everything after a MAF swap. Could my problem be injectors? Today when I put the pump is pressure was set at 45 line on. I drove it, put it back in park it had dropped to about 38 line on. I now turned it to 46 line off, but I have not gone out at another run since.

 

[ScottHeidinger]

Did you get a fuel pressure gauge you can see while you're driving? I see you replaced a lot of parts but we still need to know that the fuel pressure is rising 1:1 with boost and do you know what it is at idle? Many have trouble getting the fuel pressure low enough when running those pumps. I use one and haven't had an issue but many people have. I'm on a mobile site so I can't see your mods. What chip are you running? If it's a TT chip I would look at what timing is in the chip and for starters take a few degrees out if it's adjustable. I'm just not a fan of driving around with knock trying to figure out why I have it. How old are your injectors and have they sat for a extended period of time with fuel in them?
You say you're getting knock any time you're in boost? Even low boost?


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