80 replies to this topic

[Jimbo]

I think I fixed it via removing the OWV. Went for a trip up to the shops and it was fine...felt peaky on the primary, too.

Im not gonna get too excited until ive done the daily commute to work and back. Looking good so far!

[cowie165]

What's an OWV?

 

and w00t. Fingers crossed for tomorrow!

[Jimbo]

Ah sorry, one way valve!

Used it as a substitute for the PCS. Looks like it wasnt holding as well as i thought. Probably going all spaz under vac and boost.

Fingers crossed no symptoms tomorrow.

[Arfreedom]

Jimbo good luck on your drive tomorrow.
Can you do me a favor....when you post abbreviation like PCS and or OWV, just mention what they are in brackets and you won't have to spell out again in the chat. That way people like me that is following you would understand. Cause up to now I don't know what PCS means yet and I'm to embarrass to ask..yeah I just did


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[Jimbo]

No luck. Behaviour was still there, though it took a bit longer to set in thismorning.

Back to the drawing board..

PCS = purge control solenoid. Found under your engine cover left of the alternator. Dont touch it.

[Arfreedom]

Chaaaa
Ok car works on air, fuel, and fire....
Sit down, breathe and go through what you have done in detail and see what you missing.
Is it electrical or mechanical.... I think we ruled out electrical since it didn't throw a CEL, BUT purposefully throw a code and see what happens.
I know you will figure it out.


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[Jimbo]

It has to be mechanical which leads me to the fuel pump. Only because it's pretty much the last component which was common across both engines.

It can't be injectors or the Fuel Pressure Regulator as they were replaced by the new engine, and the behavior was present with the old engine, too.



Still haven't received the replacement Purge Control Solenoid, hopefully it shows up tomorrow and I can definitely scratch that off the list.

My thoughts with the fuel pump itself, are that perhaps it's getting a bit tired and overheating or something. It would explain why the symptom gets worse the longer you drive the car for.

It might be losing a bit of pressure or getting upset when the extra voltage is sent to it in accordance with boost, hence why the car shudders at 0psi then surges back to normal past that.

 

[cowie165]

No luck. Behaviour was still there, though it took a bit longer to set in thismorning.

 

Sorry to hear dude. I hate those gremlins.

 

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[cowie165]

My thoughts with the fuel pump itself, are that perhaps it's getting a bit tired and overheating or something. It would explain why the symptom gets worse the longer you drive the car for.

It might be losing a bit of pressure or getting upset when the extra voltage is sent to it in accordance with boost, hence why the car shudders at 0psi then surges back to normal past that.
 

 

Mebe. Do fuel pumps run a linear duty cycle or are they just switched between 33% and 100%? If low/high switched could it be 'lagging' on the low duty cycle before finally switching to give your motor the juice it needs when +ve boost? DATALOGGING! I wonder if fuel pump voltage appears on FreeSSM.

 

Did the surge happen pre-fuel filter swap? Wait, nevermind, I remember you swapped the filter trying to troubleshoot the surge

[Jimbo]

Datalogging would be just ideal right now! I bought the cable (champion!) so when it arrives, Ill run through the software and see what they all can do.

I just want this over with, doing my head in!

[duncanm]

 

Mebe. Do fuel pumps run a linear duty cycle or are they just switched between 33% and 100%? If low/high switched could it be 'lagging' on the low duty cycle before finally switching to give your motor the juice it needs when +ve boost? DATALOGGING! I wonder if fuel pump voltage appears on FreeSSM.

 

Did the surge happen pre-fuel filter swap? Wait, nevermind, I remember you swapped the filter trying to troubleshoot the surge

 

33/66/100% AFAIK

 

Yes - fuel pump duty cycle shows up on SSM.  Logging, not so much.

 

[Arfreedom]

All this talk about data logging, you know I bought a obd2 adapter and this thing only give me reading of diagnostic read out and voltage. Then I tried my friend HUD (head up display) and some thing just voltage readings. I had to call a tuner man in my country that told me about this ssm2 thing. And I went researching. Found the adapter and all but I too bought that vagcom cable just to see if it works and from Duncanm photo just convince me I me the right choice.
You guys are awesome


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[Jimbo]

Haven't had a chance to get the new fuel pump in yet (hopefully this-weekend) but I did finally get the replacement Purge Control Solenoid.

It didn't dawn on me I had ordered the PCS with the wrong plug type. The one I received had a slightly bigger plug and the locating spline was offset instead of in the middle. Whoops.

With some creative errr.....whittling... of the PCS  plug, I managed to get the harness plug into the connectors (exact same internal pin fitting, just different plug case).
Got it all bolted up, plugged in and hoses on and still no change in the annoying symptom. 

I'm down to the fuel pump now and I have one DW65C sitting right next to me here! Finger crossed this is the winning ticket!

If that one doesn't seem to do it, I purchased the same diagnostic cable as Mark and hope to do some logging to find the culprit by numbers.



The way I'm seeing it now has me pointing at the fuel system. Here's a re-cap :

- It's not logging a fault code
- Starts to occur after about ~10 minutes of driving
- Symptom is exacerbated at higher speeds
- Causes a "flat spot/blockage" experience momentarily when moving progressively from off-boost to 0psi
- Once you apply more throttle at 0psi and it makes +ive boost, you feel the power "come back on" and it's fine

What I have replaced ® or serviced (S) so far:

- Fuel filter ®
- Spark plugs ®
- Fuel pump controller ®
- Idle Control Valve (S)
- BOV adjustment (S)
- Purge Control Solenoid ®
- Upper Engine Clean (S)

Thing yet to do/suspicious item:

- Fuel pump ®
- O2 sensor (R/Inspect)
- Fuel pump relay (unlikely or car would struggle to start)
- Coolant temp sensor

If I could graph it, it would look like this. This is only a guesstimate graph and not actual data:




 

[cowie165]

For what it's worth I'm still thinking it's a fuel issue. The o2 sensor runs rich until about 10mins in, then leans it off. Your o2 sensor may well be working perfectly.

 

I agree that the pump relay is working fine.

The fuel pump functions fine at 100%DC so to me that says the signal it is getting is not correct. I still think you're right about the MAF -> When you're cruising along it might not be getting the right signal but when you plant it the ECU overrides the adjustments being made by the MAF and it just sets injectors and pump to 100%.

 

If MAF voltage is dropping out, the ECU prob thinks you're stationary and drops pump DC to 33%.

 

I'm just making this up as I go though - data cable will make your GTB tell all its cadbury secrets

[LukeFranky]

Have you tried unplugging the MAF to make the car run to a default set of fuelling values?

[Jimbo]

MAF is OEM brand new and performed perfectly. Ill have a try though and see what happens

[cowie165]

I'm pretty sure Jim's already done ECV and has def done pump controller.

 

Dude are you doing callouts now? Then come north to Newcastle! :-D

[Jimbo]

Have you tried yelling at it and threatening to sell it?

If the fuel pump isn't the solution, what's next?
Pump controller?
ECV adjustment?
Line 1 mod?

We'll chat tomorrow anyway, cubt.

Knock off pump controller and ECV adjustment, done them both. TT operation is super sweet and functioning as it should!

If we get time, we'll go for a spin and I'll show what it's doing. Though, betcha anything it wont do it if you drive..... 

 

[Arfreedom]

Yeah!!!!! For Jimbo


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