V70 T5 misfire
 

Happy holidays chaps.

I've been floating around for a while, but seen as the V70 never caused me any issues (until now), I rarely post. I was unsure whether to stick this in the lpg or V70 forum, but if i got it wrong, please move the post Mr mods..

I have a 2000 MK2 V70 T5 with an ESGI lpg kit that i fitted nearly a year ago. Things had been running excellently and covered 30k miles until last week when i developed a slight misfire under heavy load with P0302 occasionally thrown for Cyl2 misfire. It only misfires on gas, perfect on petrol.

After checking the maps and fuel trims, all seeemed fine and dandy (lpg map follows the petrol map perfectly with fuel trims at 5% long term), so out of interested I swapped the injector (as I have 3 spare, all new) and went for a drive. Nothing changed, still a misfire on cyl2.

I then swapped the coil pack and plug from cyl2 to cyl1 and went for another drive but still P0302 code is thrown. The misfire grew steadily worse throughout the day and so I pulled all the hoses off and checked for leaks and found nothing on the gas or Volvo pipework. Wiring also looks fine and all earths have been cleaned.

Now here's the kicker, in the ESGI software I have the option to run individual cylinders on petrol or lpg and so I switched cyl2 onto petrol and the other 4 cyls on gas and the car runs perfectly smooth, if a little down on power. Any combination of fuel/cylinders caused misfire unless cyl2 runs petrol, then all is good.

So, I'm guessing it's time to dig out the compression tester and look for a possible imbalance between cylinders but while I try and find the bugger, can anyone suggest anything i've missed?

The car is running:
ESGI ecu
Magic jet reducer set to 1.3bar and running both lpg outlets
Valtek type 30 (3 ohm) injectors drilled to either 3mm, or 3.2mm (i forget which at the minute)
Car has covered 170k miles, the last 30k on lpg in the last 10/11 months.

Thanks in advance of any suggestions..

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Could you possible run the following test's on petrol with the engine warm and scan tool in live data;

1. Idle speed and note the short term fuel trim.

2. 1500 rpm for 30 seconds and note the short term fuel trim.

3. 2500rpm for 30 seconds and note the short term fuel trim.

I certainly can, i'll look this evening.

I've observed the fuel trims while both on petrol and gas when driving, nothing came up out of the ordinary. I'll certainly post some results up for your tests later.

Ok, managed to take a look.

At idle, short term hovered around 1.55%
1500 rpm was +/- 2%
2500 rpm was from -7 to +3%.

I forgot to mention at the first post that it sometimes cuts out if left idling for a few minutes and is difficult to restart, only usually restarts if throttle is held wide open.

Short tem trims are perfect to rules out a air leak in the area of cyl2. changing over the coil pack and plug would eliminate ignition. fault is defiantly cylinder specific, you say you have a compression gauge do you also have a vacuum gauge?

Have you replaced the spark plugs yet? Make sure you use normal plugs and avoid any plugs that claim to be LPG plugs that are sold on the net.

You have done well so far getting 30k out of the type 30 injectors as they are not known for reliability and are only normally packed in the cheap budget bundles.

Where is the vacuum pipe positioned for the map sensor and vapouriser? is it anywhere near cylinder 2?

I have a vacuum gauge, yes. What are you thinking?

Plugs have done less that 4k miles and are BKR7's. I have swapped the plugs around however and still the misfire is reported on Cyl2.

Vacuum take of for the vaporiser is right on the end of the inlet manifold, next to Cyl5.

do you have enough posts to pm?

I have 46 posts fella. How many are needed?

30 posts is all you need to PM