Feels like it wants to stall Topic is solved

Post by **abscate** » 03 Mar 2021, 07:35

Deposits are normal and can be many colours. You cant diagnose spark plugs like you could in the old days, unless they are gunked up with oil and coke - then you need a new engine.

Post by **Sveedy** » 03 Mar 2021, 09:07

Yea I was probably unnecessarily hung up over the color of the sensor. I looked up symptoms of a bad MAF and they sound like what I'm experiencing. So I'll head back to the JY and grab a MAF. Would have gotten it yesterday but they want $ 40.00 for the old thing.

I've heard that JY prices are going up in part to try and shake us off our old cars and buy new ones. Insurance companies are also in on it, totaling older cars out even when the damage isn't that severe. Happened to a friend of mine, who questioned why his car was being totaled out due to a fender bender. Straight from the insurance guys mouth - " We want all these old cars off the roads ".

Post by **Sveedy** » 03 Mar 2021, 14:55

Installed the JY replacement MAF and no change. I guess that one could be bad as well. While trying to start it I got a CEL - PO102
Mass or volume air flow A and Circuit low input. Unplugged the MAF and car started but then started to stumble and threw that code.
So now I'm at a loss. Hate to buy a new MAF and still have this problem. And o2 sensor checks out fine, according to the datalog I sent to the tuner.

Post by **Sveedy** » 03 Mar 2021, 17:11

Figured it out. I sent a datalog to the tuner and he saw something in the boost circuit that is not right. He said O2 looks great.
I switched out my tuned ECU, 4.4, for the original one and the car started right up and idled fine. I little rough the more it warmed up but with the mods I have on there I would expect the 4.3 to be out of sorts.
So problem solved !

Thanks to all of you AGAIN for your help !!

Post by **Sveedy** » 05 Mar 2021, 17:46

So I'm curious; could I use my stock 4.3 ECU for a short time if my 4.4 is temporally down ? I tried it and only noticed a drop in boost / acceleration. My concern is with the white injectors instead of stock orange ones and different fuel pump. Am I just likely to be running rich ?

Post by **abscate** » 06 Mar 2021, 04:27

Probably ok. If the fuel pressure is the same the ECZu will close loop with the oxygen sensor and correct the injection time to get the right oxygen content, ergo,mixture.

That’s my educated guess, I’m only an I-Tunes expert

Post by **Sveedy** » 06 Mar 2021, 15:30

Argh !! The problem persists even after fixing the ECU. And the stock one won't work anymore either. Hard to start. Idle fluctuates between 600-1300rpm and would stall if I didn't intervene. Really pronounced in park. If I try and drive, it stumbles and bucks if I give it much peddle. So I pulled the plugs and they were carbon fouled. Plugs, wires, cap, etc all a little over a year old and all the recommended parts. At this point I have taken everything apart and put it all back together. Tried a different MAF but no change.
The only thing in the fuel system I haven't replaced is the fuel regulator. Could age and the bigger fuel pump have blown the regulator and cause these problems ?
Does a fuel pressure reg. experience more stress at WOT ?

Post by **Sveedy** » 07 Mar 2021, 11:11

Hoping I might be on to something here.
Fuel pressure is a steady 43psi @ idle and holds about 11 after shut off. So I think that is all good. However I read about the proper way to check the MAF, that being to disconnect it while the car is off, not while it's idling. With the MAF unplugged the car holds idle, though it's a tad uneven (+- 50rpm ). With the MAF plugged in, I have the wide fluctuation at idle, with it going from 600-1200+-rpm. This is with both MAF's that I have, so I'm thinking that they are both bad. Does this sound reasonable ? How well should the car idle with the MAF disconnected ? It's not perfect like normal but it's not bad.

Post by **Sveedy** » 12 Mar 2021, 21:39

Installed new MAF. No change. Built a small smoke can tester to check for intake leaks. Good news - There weren't any.
Bad news - The problem persists. So could I have a leak around the pick-up pipe / hose connection inside the fuel pump housing and still have perfect fuel psi at the fuel rail ? I'd rather not pull the pump and chance hurting the o-ring on the tank if I don't have to.

Post by **misha** » 13 Mar 2021, 02:24

Fuel pump housing o-ring is 6€ from volvo dealer(around 5$).
I bought 2 few months ago to have it for spare.
If spark plugs are black and covered with carbon...car is overfueling.

You should have fpr on fuel rail.

So...check this out:
-disconnect maf connector and remove vacuum line from fpr and cap the other side which goes to the vacuum tree,start the car and look for fuel leaks from fpr's vacuum side.
Idle it for 10-15 minutes because if there is a small leak from the fpr membrane it could leak after the engine runs for a while.

If it runs better with maf disconneted....that's it.

But....since you allready replaced it with brand new one(i hope it's oem Bosch)....the connector could be bad(it's more prone to failure than actual Maf sensor).

Other than all of this mentioned above....could be bad injector/s.

ECT?
It could also be bad...but it's wiring is also more prone to failure....wiring from the engine wiring loom side.

Try with removing negative battery cable for 10-15min in order to reset fuel trims and see if it would run better.

But....again....if it runs better with maf disconnected and you allready have brand new oem Maf....the connector might be at fault.

Feels like it wants to stall Topic is solved

Re: Feels like it wants to stall