Issue developed with fuel delivery

[scoobydo123]

Please throw some ideas at me. Nissan Ka24de(t) that suddenly has running issues. Car starts perfect and during warmup afr's are where they are usually at, varying by 0.2 and engine is stable. However once engine gets to around 50c things start going down hill with afr from my targeted 14.6 going lean and to 15.8 and rich 13.6. Normally I have a stable idle with only .2.variation, engine also goes jumpy with 150 rpm drop.Have turned o2 feedback off just in case o2 sensor has gone funky to no avail. What I have noticed whilst fishing around the engine is the the flow to the injector rail and the return have a strong pulsing motion to them. Don't know if it was normally like this. Also disabled idle feedback for the IACV.

Ecu AEM v2
fuel rail Greedy
750 RC injectors
Fuel lab fpr with small gauge attached
Haven't found a fuel pulse damper but ran fine for last 10 years of my ownership without.


One thing of note I did recently fill the tank from Jerry cans but used probably 1/8th of a tank has gone through since then.

The difference between warm up and normal running is night and day. Also if I try to rev it up afr go super lean in the 17's.

Edited by scoobydo123 on Friday 27th June 06:50

[E-bmw]

You say "flow to the injector rail is pulsing" firstly, how have you determined this and what is the fuel rail pressure doing during this "pulsing"?

Have you checked the inlet manifold to MAF area for air leaks?

Where/how are you testing your AFR readings?

[scoobydo123]

Hi thanks for the interest ;-) if I hold the rubber fuel hose either on the flow or return to the tank I can feel the strong pulsing.

The small pressure gauge on the fpr doesn't seem to pulse however I am not sure if the gauge is large enough to show what is going on.

AFR is from the widebamd gauge and also what the ECU reads.

Sorry it's MAP based rather than MAF but guess same applies reference air leaks. Cannot hear anything out the normal. I do have a homemade smoke machine thst is not the best but found injector seal leaks before.

Idle quality between warmup and when around 50c is night and day warmup is perfectly smooth

Edited by scoobydo123 on Friday 27th June 09:19

[paul_c123]

Is it in closed loop?

What are the fuel trims?

Is it remapped?

[scoobydo123]

It is standaloneAEM v2

Have turned of closed loop to rule out the o2 sensor and still have the issue.

Thanks

Edited by scoobydo123 on Friday 27th June 10:49

[E-bmw]

scoobydo123 said:

Hi thanks for the interest ;-) if I hold the rubber fuel hose either on the flow or return to the tank I can feel the strong pulsing.

The small pressure gauge on the fpr doesn't seem to pulse however I am not sure if the gauge is large enough to show what is going on.

What pressure is the gauge reading & does it go to zero if you drain the fuel rail/remove the gauge, can you test it against an air pump or similar?

[paul_c123]

Sounds like a failing or blocked fuel pump. The direction to diagnose this would be to look at fuel pressure as revs and load rise. If all is good there, it could be the injectors.

[scoobydo123]

[/quote]

What pressure is the gauge reading & does it go to zero if you drain the fuel rail/remove the gauge, can you test it against an air pump or similar?
[/quote]

Shows 3bar at idle and when the engine is switched off it drops to just over 2bar IIRC and the holds this pressure for a good few hours. I do have a large dial fuel pressure gauge that I can tee in.

[scoobydo123]

paul_c123 said:

Sounds like a failing or blocked fuel pump. The direction to diagnose this would be to look at fuel pressure as revs and load rise. If all is good there, it could be the injectors.

That's the angle I was going at this pulsing I can feel is quite pronounced just wish I knew if it was like that previously. What I find strange is how good during warmup things seem but once near up to temp it starts running rough. Should I guess also make sure battery voltage is not dropping off for some reason. It is like that either after x time something starts breaking down or X temp. Have changed plug leads, will try spark plugs. Maybe also upload a video / ecu logs. Anyone around Romford Essex that could take a look?

[GreenV8S]

It's normal for the fuel pressure to pulse slightly - fuel pressure gauges are usually damped to smooth this out. But if you're feeling it in the hoses this seems like more than that.

The engine would usually run richer during a cold start. The fact it starts misbehaving as soon as you end this enrichment suggests that the problem is caused by running lean. Possible causes are low fuel pressure, ECU pulling fuel due to EGO feedback, blocked injectors. Combining this with the pulsing you mentioned, and I'd start by suspecting the fuel supply side: possible pump failure, possible electrical problem, possible FPR problem. If the fuel pressure is erratic then the AFR will be erratic and it would lead to these symptoms.

I'm not familiar with that engine, but since you mention having a FPR I assume that the pump just needs to be plumbed in and powered, and doesn't get involved in modulating the supply pressure. That makes it relatively simple to jerry-rig for testing. If you want to DIY this you could hotwire a power supply to the pump, if that doesn't help then rig up an external fuel pump and fuel source.

[E-bmw]

scoobydo123 said:

Shows 3bar at idle and when the engine is switched off it drops to just over 2bar IIRC and the holds this pressure for a good few hours. I do have a large dial fuel pressure gauge that I can tee in.

OK, it NEEDS to drop to zero when removed from the fuel rail or after the fuel has all settled or else it sounds like you COULD have a gauge stuck at 2 bar & are just putting 1 bar of fuel pressure into the fuel rail.

This would 100% explain the issue you are seeing.

Not saying it 100% IS the issue, but it would certainly explain it.

ETA what pressure does it go up to if you rev the engine?

[scoobydo123]

Yes suspect fuel delivery issue. I have disabled o2 feedback and ign timing feedback with no real change also if I adjust the map things don't respond like they normally do. Maybe the pump as you say is on its way out and it starts off OK and then starts acting up. Fuel pump is an in tank job so bit of a pain and was upgraded by previous owner not sure of spec or brand. Maybe the intank fuel line was the incorrect type or maybe fuel filter blockage. Trying to see if there is a way I can diagnose with the least disruption ;-) I like the idea of Jerry rig something up but I would have to see what in tank one us currently in place so can buy one of those for if it is proven as on the way out.

Edited by scoobydo123 on Friday 27th June 14:07

[scoobydo123]

E-bmw said:

OK, it NEEDS to drop to zero when removed from the fuel rail or after the fuel has all settled or else it sounds like you COULD have a gauge stuck at 2 bar & are just putting 1 bar of fuel pressure into the fuel rail.

Ah I may have mislead you there what I was saying is that if I switch of the engine the pressure does not bleed of immediately. If I relieve the pressure the the gauge drops to zero as it should.

[E-bmw]

scoobydo123 said:

E-bmw said:

OK, it NEEDS to drop to zero when removed from the fuel rail or after the fuel has all settled or else it sounds like you COULD have a gauge stuck at 2 bar & are just putting 1 bar of fuel pressure into the fuel rail.

Ah I may have mislead you there what I was saying is that if I switch of the engine the pressure does not bleed of immediately. If I relieve the pressure the the gauge drops to zero as it should.

OK, that is different.

The other question stands, what does it go up to when you rev the engine?

[scoobydo123]

E-bmw said:

The other question stands, what does it go up to when you rev the engine?

Hi I will get that info to you when I am back with the car. Plan is change plugs incase plug issue. Capture logs amd take note of fuel pressure gauge.

[E-bmw]

Looking through your posts, you don't seem to mention whether this is when driving the car, or just statically warming it up?

[scoobydo123]

OK so rev up cause the fuel pressure to increase but with a slight vibration on the needle. This is just with the car warming up.

Changed the plugs and have a marked improvement to the situation currently. Maybe the plugs ngk bkr7 have gone faulty I did previously clean them with map gas blow lamp however they were fine but maybe I damaged them.

Still obviously have the pulsing on the fuel pump not sure if this is just the injectors opening and closing but the rail and injectors don't pulse the same as what I can feel on the pipe.

[stevieturbo]

so just check fuel pressure ?

[scoobydo123]

Interesting as well but not related I can see in the logs that even now and again I get accel fuel 0.570ms and throttle going to 3.8pc so need to adjust that.

[GreenV8S]

Is this a standard car which hasn't had any changes or other problems prior to these symptoms?