Anyone have any ideas on this problem? FINALLY SOLVED

[sk47]

are they both on the throttle Body and the accelerator pedal?.

Hello; I do not know on the Mustang for sure but suspect on the throttle body. On my 24 year old car the linkage is mechanical from the gas pedal.
On my slightly newer truck there is no mechanical linkage. It is fly-by-wire so to speak. The pedal sends a "radio" signal to a motor on the throttle body which opens and closes the throttle venturi. This is why my truck could have a "tune" so as to alter the gas pedal response.
For what it i worth I prefer my old car. I can "tune" the throttle response with my foot.

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[Leigh_bullitt]

Really appreciate your input to my problem.

I mainly use shell 98 octane ( Europe ) I believe all gas over here is Ethanol 5% only.

 

[sk47]

I asked him earlier about his fuel quality. He s in another country and I don t want to assume. BUT again, he said it s been like this since new so.... pump?

Hello; Another wild thought. Most dealers keep low fuel while a car sits on the lot. They may give you a full tank at purchase. Say the new owner parks the car a lot, rarely drives and keeps the tank low?????

 

[Leigh_bullitt]

So I think plan of action will be….

1. remove throttle pedal and check its all ok.
2. Run a datalog of all throttle pids and see if something is acting erratic

3. Check the fuel pump. I know the HPFP is getting enough fuel because it’s pretty much matching specified although sometimes I have noticed the pressure much higher than specified.

4. if none of the above I’ll move on to plugs and coils

no vacuum leaks and Maf is working perfectly.

5. I may also remove the intake manifold and check IMRC runners in case they are getting stuck maybe?.

 

[sk47]

it's just throwing parts at it but it is a mystery.

I d start with the cheapest . Consider some of it maintenance anyway.

BUT again, he said it s been like this since new so.... pump?

Hello; I agree to start with the cheapest parts to throw at a problem when there is no good indicators. So why not a pump

 

[SheepDog]

One thing I can think of that may cause this, is a bad purge valve.

Have you messed with any of the wiring in the engine bay? A loose ground wire might cause these symptoms too

 

[Leigh_bullitt]

I did suspect purge valve a while back and replaced it but no change.

 

[Cobra Jet]

Sounds like a possible VCT issue.
It’s possible the VCT’s have debris in them. You can do a cycle on them to try and cleanse the debris from them. VCT’s are known to cause quite a few idle/annoyances with these Coyotes….

Also to note, even if there is debris, the PCM won’t always throw a code, it only throws the hard code in an extreme instance of an “on/off” sensor event.

The culprit here was the VCT solenoid::
https://www.mustang6g.com/forums/th...s-and-cam-retarded-codes.176734/#post-3571964

Here's (2) more threads for VCT info that I had previously posted in other threads:
https://www.mustang6g.com/forums/threads/p0018-code.123932/page-2#post-2646415

https://www.mustang6g.com/forums/threads/2015-2021-s550-5-0’s-ssm-50067-vct’s-again-various-dtc-codes.169419/

IMRC system could cause drivability/idle issues as well and it won’t always throw codes if it’s acting up. There’s tons of threads on here RE: IMRC.

I know it’s been asked, but what (if any) codes are you getting?

 

[Leigh_bullitt]

Cheers
Yes I did check and suspect the VCTs first off a while back but they are all working within spec and not throwing any codes.

they do rattle on cold start for about 30 seconds and I can hear them around 2k clicking away but they seem to be working fine. I was thinking about cleaning them with a 12v battery and clicking them on and off at the terminals on the solenoid. They are all working within spec on FORScan
-0,006 to 0,012. The other holds firm 20,00
All within spec I believe.

 

[Leigh_bullitt]

Managed to get an Sct x4 screenshot while the engine was running amazing. Screenshot was at idle and had been siting for a while which is why the intake temp is high.

does it look like I’m running too lean ?
It’s lean but I don’t think it’s that bad.
between 3-4% correction

 

[Leigh_bullitt]

Do these figures look ok to anyone ?.
This was at idle. Why is the fuel pressure so high compared to specified ?

 

[sk47]

kpa to psi - Search

Hello; Been a while since I figured with KPa ( kilo pascals) so I had to look up the conversion. The numbers in your post come out very high. What have I missed?

 

[sk47]

Hello; using the conversion link I get 7580 kPa = 1099 psi
14700 kPa = 2132 psi.

 

[Leigh_bullitt]

It stays like that until I rev the engine and then it settles down again.
On some other forums apparently is normal for tunes to do this and nothing to worry about.
How would I log the fuel pump duty ?.
anything I should be looking out for ?.

 

[sk47]

It stays like that until I rev the engine and then it settles down again.
On some other forums apparently is normal for tunes to do this and nothing to worry about.
How would I log the fuel pump duty ?.
anything I should be looking out for ?.

Hello; I gather you use a Sct x4 tuner to create a tune and also manage to get the readings you have posted. As I do not have experience with these tuners, I cannot say one way or another about the quality/accuracy of the readings. I do assume the tuner gets readings from the factory sensors attached to the engine. If such is correct, then a situation might exist where some sensor is out of spec and trusting the readings is possibly questionable. Regardless you are walking the walk by gathering data and evidence. Hopefully it will make sense someday.

The fuel pressure seems high, but it may be normal. A friends 911 T has mechanical fuel injection. An electric fuel pump feed lower pressure fuel to the high-pressure mechanical fuel pump system. I think direct injection engines run at higher fuel pressure. It would see the fuel system is running at roughly twice the required pressure. So this should indicate the fuel pump(s) are working fine. A question is where these readings taken during a period of the rough running which has been plaguing your engine??? If so, then a tentative but not final conclusion could be the fuel pump(s) are in good order.

A thing to look for is if the fuel rails hold pressure with the key turned off. Can you get such readings say an hour after turning off the engine?

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