Feels like it wants to stall Topic is solved

Post by **Sveedy** » 13 Mar 2021, 08:19

Thanks Misha ! I'll try that today.
ECT replaced. Injectors and pump replaced. At this point the car is built around the tuned ECU so I'm running the white injectors. Bremi Maf but I also have two Bosch ones that are used. All behave the same way.
Would I still have 43psi at the rail if fuel was getting around the pipe/hose connection inside the pump housing ? I know people have had issues with that connection after pump replacement and the tuner said that might be my problem. He said my fuel trims are all over the charts; long term pulling in a ton of fuel, while short term ones are going from max to min. So car won't run.

What is puzzling me is that the car won't idle or drive with my tuned 4.4 ECU but if I reinstall my stock 4.3 then the car idles and drives ok. How can it work with one ECU but not the other if something other than the ECU is at fault ? Drove it 60 miles yesterday - stop and go traffic as well as highway. Not perfect until warm but then a steady 900 rpm no mater how long I let it run. Shut down and restart and still idles fine. Even sat in a drive through line for 10 min and it just purred. But seems to not have any boost to speak of. Will idle perfectly and run up to and cruise at 75mph with out problem. But again no boost. Kind of feels like a NA car. Dash boost gauge moves but not as far into the white as with the tuned ECU. So my thought is that my basic systems / sensors must be alright since things seem to be so much better running the stock ECU and that maybe the problem is with the tuned ECU reading and applying the info its being fed it from the sensors. I just have no idea at this point.

After a couple of weeks of this and I'm about ready to through in the towel and take it to a shop.

Post by **Sveedy** » 13 Mar 2021, 10:22

" 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. "

Sorry Misha but I don't quite get this description of what to do. So one line goes into fpr and one goes out. Do I disconnect the fpr line that goes to the vacuum tree ( out ) and cap both that port on the fpr and the open port on the vacuum tree ?

Post by **misha** » 13 Mar 2021, 15:47

Remove the vacuum line directly from FPR and cap it.
This will not introduce a vacuum leak while engine is running.

Bremi will not work....but you're right...something is going on with tuned ecu....if it runs and drives ok with stock one.

Post by **Sveedy** » 24 Mar 2021, 19:33

So I wanted to close out this thread with what ended up being the problem. After spending way way too much time going down different rabbit holes with no success, I threw in the towel and took the car in to a indy shop for diagnosis. The mechanic drove it with both ECU's and couldn't really explain why it drove better on the stock one. They connected up a " real " smoke machine, unlike my little can deal. Nothing at first, but when they put it up on the lift, they found that I had a cracked / separated intercooler

I had no idea that the stock intercooler had a plastic tank ! So yeah I could see how that would fail after 25 years of heat, followed by my modifications.
Now I have a nice do88 instead. He also strongly recommended that I put in a catch can system, which I had him do as well. Car runs GREAT !

Moral of the story ( ok there are a few in there ) - The first idea as to what the problem was, induction leak in my case, showed to be true.

Thank you all !

Post by **abscate** » 25 Mar 2021, 04:57

I missed this post but this was the tip off

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.

If it goes stable when the car is run without the MAF plugged in , it’s indicative of induction leaks. It’s important to unplug the MAF with the car stopped, then start.

Without the MAF, the ECU uses rpm to meter fuel which works well at idle.

Did you get your old intercooler back? Interested in where on the plastic it failed.

Post by **Sveedy** » 25 Mar 2021, 16:34

Didn't pick it up, but I'll be right around the corner from them tomorrow so I think I'll stop in and look at it.
Plastic - my favorite material

Post by **abscate** » 26 Mar 2021, 04:16

It does suck when plastic parts fail, but the weight saved in a Volvo is added to the steel that protects my seven ladies,something for which I am grateful

Post by **Sveedy** » 26 Mar 2021, 06:39

Not just when the stuff fails, but all the way through from production to disposal. I don't think we know,or have been told, the real cost of that crap. Hopefully we'll move on from it quickly....though the damage will be with us for a very very long time.

My early morning Friday rant before tea.....

Feels like it wants to stall Topic is solved

Re: Feels like it wants to stall