1997 v70 T5 Stutter at WOT on T5

[scot850]

Resetting the codes just means the ECU takes some time to check the readings before realising the issue is still there.

Fuel pressure is definitely needing checked to at least eliminating it from the issues.

Have you checked if any oil has leaked into the distributor cap? If the oil seal leaks into the base of the distributor it can cause chaos in the running of the engine.

Another simple thing to check is the routing of the cam sensor cable where it runs near the distributor. If it runs too close it can cause signal issues in the signal to the cam sensor.

Final thing is removing the ECU and check the connections for corrosion.

Neil.

[Fiodor]

Resetting the codes just means the ECU takes some time to check the readings before realising the issue is still there.

Fuel pressure is definitely needing checked to at least eliminating it from the issues.

Have you checked if any oil has leaked into the distributor cap? If the oil seal leaks into the base of the distributor it can cause chaos in the running of the engine.

Another simple thing to check is the routing of the cam sensor cable where it runs near the distributor. If it runs too close it can cause signal issues in the signal to the cam sensor.

Final thing is removing the ECU and check the connections for corrosion.

Neil.

I'll check the distributor tomorrow.
The ECU connections are perfectly fine.
I'll try to get ahold of my mechanic in the upcoming week.
Would hooking up a bicycle pump to the fuel rail give me a good approximation of the fuel pressure or do I need to use a special tool ?

[wizechatmgr]

Battery is brand new, Fulmen 640A and 64 Ah.
I haven't removed the piggyback thingy, once my tank's empty I'll switch to regular gas and remove the piggyback apparatus.

Any chance you can post some information on the piggyback thing you're using for E85?

[scot850]

Do you mean a bicycle pressure tester? A pump won't help you unless I am missing what you are trying to tell us.

A regular pressure gauge like a tire pressure gauge (one of those metal slider types) might give you a static pressure but not what is being seen when under WOT.

Neil.

[Fiodor]

Battery is brand new, Fulmen 640A and 64 Ah.
I haven't removed the piggyback thingy, once my tank's empty I'll switch to regular gas and remove the piggyback apparatus.

Any chance you can post some information on the piggyback thing you're using for E85?

I bought this kind of thing on Aliexpress for 80 euros:
https://www.boitier-e85.com/en/product/ ... -starflex/

It basically multiplies the injector opening rate by a factor which you can set via a potentiometer in the box.
Has worked without issues for 3 years (appx 7000km).
In France a tank of gasoline costs roughly 100 euros and a tank of e85 costs 30 euros.

[Fiodor]

Some updates:
I replaced the intercooler with a do88 unit (glad I had a friend to help me!), didn't solve my issues ofc.
BUT ! I now have STFT and LTFT back for some odd reason.
I logged the voltage from my oxygen sensors and it seems a bit weird, could one of you educated people look at my curves

The second one seems like it has a slight issue ?

Also, my exhaust is now popping on deceleration ?

[abscate]

I think your second OXS is high, should be closer to 0.5 V , but confirm that please

High voltage is a Rich fuel air ratio, too much fuel

The swing on the upstream sensor looks normal. That one gets dithered back and forth to close loop,on the injection volume

[Fiodor]

The plot thickens, had some trouble starting the car this morning and this afternoon, I filmed the afternoon start.


Car drove perfectly fine afterwards (with the stutter coming back after 8km).

[hausmeister]

I logged the voltage from my oxygen sensors and it seems a bit weird, could one of you educated people look at my curves
The second one seems like it has a slight issue ?

Also, my exhaust is now popping on deceleration ?

I wouldn't know what to make of these curves...

But you are saying popping exhaust, that I have experienced. Imo: Boost leak, vacuum leak, bad hose etc. At least that is what caused it for me. I guess the AFM senses still air flowing (escaping) which means it runs too rich and you get the popping... (?)
Would also explain why it runs like shit, and if you have a leak then sure, it won't have power.
(Or just a bad AFM)

Well, no way to know for sure, but if I have learned one thing during my 850 journey, it is that even if you think you have fixed all leaks there are probably more
Get a pressure testing kit, check the small Idle air controller hose... that is where I would start.

You said something about do88 rip kit? Which I also have. Check the hose clamp on the short hose directly on the turbo. I had trouble getting that one to stay on, and even when it was on it was leaking - which I only know because I replaced it with one of the heavy duty calmps and that fixed it (more power, no more backfarts).

[Fiodor]

I'll check that small hose once more
Idle valve hose has been replaced with do88 as well but I'll check the clamps too.
Bought a fuel manometer yesterday and I'm expecting it to arrive today, I'll update the post once I've gotten the fuel readings.
Should I measure the pressure at idle + revving or should I hook a long fuel hose into the cabin and check during real pulls ?