VT Dual Fuel slowly loses power on petrol when warmed up

[lignum1966]

Hi there , first up my Vt is Ecotech V6 , dual fuel , pretty stock , just Big CAI and Hi flow filter , Supercat Catback exhaust and Mace Enginering ECU chip .
(and of course dual fuel) . Christmas before last I put a fuel injector rebuild kit through it . (filter pots , o-rings and pindle caps)
Car was running so bad on petrol recently it would basically start and idle but stall out as soon as I went to rev it a little . Had been getting worse on and off for a while so
last weekend I removed the fuel tank , cleaned it out , replaced the complete pump unit that was very disgusting , dirty , blocked and rusty looking . Replaced fuel filter and fuelled the car up (I used Caltex 98) (Thats almost gone now so I'm gonna try something different but in this case I don't see it being that fuel) . Started pretty well straight away on petrol , revved freely and drove nice in a quick test . However all wasn't as good on the way to work next day after the car had warmed up !

So the car still runs fine on Gas , hot or cold . On petrol it starts anytime and runs fine when cold , but as it gets up to running temp starts to feel a loss of power and slightly rougher running (missing or surging) at or around around 1500 rpm approx which is 60kph in 3rd approx (and the same in top around 80ish) , and then generally starts to run worse and lose more and more power till undriveable or close to it . However I flick it back on gas and it runs just fine again . Now the Mace chip is a recent addition but the fuel problem seems to be there with that chip or the original ecu chip in use .

I don't know much about fuel regulators , cant find any obviously damaged or leaking vacuum lines , and (maybe stupidly) have sort of discounted electrical problems as the car always seems to be fine if I run on gas .

Hours of reading either here or on google and mostly getting sidetracked with other posts have made me no wiser (as to this problem at least) ... so I'm hoping someone here can !

Bazz

 

[dirty hands]

just saw you have an EGR question as well -- if faulty code 18 or 29

if no better

low fuel line pressure when hot

you have done the tank /fuel pump and filter
injector 0 rings not leaking
no smell of petrol
cant see it being injectors them selves if ok on gas
not a coil pack or DFI problem gas runs perfect

have you cleaned the thottle body and or cleaned /checked the MAF

correct - fuel pressure regulator is vacume operated - no code will exist

if no vacume leak there --- did you know a faulty fuel regulator can sometimes fill up with petrol

think about checking then replacing the fuel pressure regulator - shares both injector lines ---wait and see if it improves

 

[EYY]

Has it ever backfired on gas?

 

[lignum1966]

Thanks for the replies , I cleaned the maf and in fact swapped it out with a couple of spares I have to try as well (no guarantees on the spares though) , haven't yet cleaned throttle body since I did the injectors .
Never backfired on gas or petrol .
I have an ALDL cable so I'll have to hook the lappy up and see if I can find any other related errors with the provided software . I've never had the check engine light come on using petrol , does occasionally come on for a little while using gas but then again it has done since I had the gas system fitted 3 yrs ago . Had both o2 sensors replaced at that stage although I suspect they were fine and the gas fitter just didn't quite get something perfect when installing but has always run well enough on gas to keep me happy as I use petrol 75% of the time anyway .

I only replied in the other thread as this one didn't seem to post when I tried - maybe just a delay for moderators to check it first as I'm new to posting here , anyway I thought that problem might be something similar .

Oh , is there a way of testing the regulator or pressure ?

 

[lignum1966]

After hooking up my car to my laptop it has apparently recovered the following error codes

Set DTC 45 - rich exhaust
Set DTC 57 - injector monitor line failure
Set DTC 65 - left side 02 rich
Set DTC 76 - c/l integrator failure
Set DTC 92 - low fan communication error

The software is TunerPro RT .

 

[GMDriver]

DTC 92, usually sets when the laptop is hooked up to the OBD plug & you have engine running, just clear the fault with the ignition on (engine not running)when your done.
If it still logs without the engine running check your fan relays/fuses
DTC 57, that will set when your running LPG as the volts to the injectors is cut off.

The other DTC 45,65 should all be related to the LHS 02 sensor, check it hasn't come unplugged, if not replace both sides
DTC 76 sets when 1 bank (side) is running way richer/leaner than the other

 

[dirty hands]

Oh , is there a way of testing the regulator or pressure ?

injector fuel line pressure needs a gauge ..bit more complicated

any vacume device
old school way
a piece of vaccume hose on the regulator --suck in the air

block off the hose with your tongue---- if it holds pressure ..should be ok

 

[Nut Kracker]

You're say as it gets hotter the engine gets worse.......
I'm wondering if the CTS (coolant temperature sensor) is faulty,
therefore giving the PCM incorrect information, regarding the proper fuel delivery to
the engine, as it gets hotter.
This 'could set the rich exhaust codes etc.

When the engine is cold, the CTS tells the PCM to delivery more fuel (quicker injector pulse rate).
Sort of like an electronic choke.
As the engine's temperature rises, the value of the CTS changes, relates that to the PCM and the fuel decreases.
Just like pushing the choke in.

 

[lignum1966]

DTC 92, usually sets when the laptop is hooked up to the OBD plug & you have engine running, just clear the fault with the ignition on (engine not running)when your done.
If it still logs without the engine running check your fan relays/fuses
DTC 57, that will set when your running LPG as the volts to the injectors is cut off.

The other DTC 45,65 should all be related to the LHS 02 sensor, check it hasn't come unplugged, if not replace both sides
DTC 76 sets when 1 bank (side) is running way richer/leaner than the other

I'm with ya thinking about the 02 sensor as that apparently sets of the check engine light , however it only sets it off when running on gas . I'll have to try to clear the codes again (couldn't clear them for some reason or other last night , maybe the software doesn't like windows 8.1 entirely or maybe I was just tired) but anyway , then I can start and run the car on petrol and drive until it has another dummy spit and hopefully be able to pull over to scan for errors again before switching back to gas .
Maybe an idea to remove the Mace performance chip for the time being just to be sure altho once again it runs good on gas with the chip installed (different octane rating tho) .
I should add when it starts to crap out , say trying to mildly accelerate from 57-58kph up to say 65 it starts to shudder almost like a corrugated dirt rd and this gets worse too .
Now Nutcracker has me thinking too about this other sensor which sounds . More reading to do yet , cheers guys .

Oh , thanks Dirtyhands too by the way , I did ask the mechanic at work about that today but he said the symptoms dont match the fuel regulator .

 

[GMDriver]

Now Nutcracker has me thinking too about this other sensor which sounds .

i'd doubt it seeing you have no fault code for the coolant temp sensor,
The other thing is to look at the temp in dashboard mode on your laptop, if its a stable temp (around 80 deg) fully heated up, & not fluctuating the sensor will be fine.
Go with the codes its telling you, its running rich 1 side....
Good luck