Excel

Hi all,

I have a 1999 Express cutaway RV with the 7.4 vortec which i have owned for a year now, since i bought it i found when first started the idle goes up and down from cold then steadies as it warms up then when i try to pull away the engine starts misfiring, popping back through the inlet at about half throttle then clears and off she goes and this doesnt happen again until it is switched off and restarted and doesnt matter if its hot or cold.

One thing i did notice is the ''check engine soon'' light was on and found the sealing ring had split on the filler cap so i bought a lockable cap, fitted it and the light went out for a while then came back on. i got it to go out again after removing the fuel cap and refitting it again?

I fitted a set of spark plugs to find 3 of the plugs really smelt of fuel (had been stood for a week after a run) and apart from that i havent tried anything else.

MPG is around 5-6mpg and feels underpowered.

I also forgot to mention this also runs on LPG and runs smoother than when on petrol.

Could a semi blocked fuel filter cause the above problems?

Sorry for the long first post but i really hope someone can help give me some ideas as i cant find anyone with any experience with this engine here in the UK.

Thanks in advance for any help

canucklehead

Get the codes read to see what the cel light was for. Could just be for random misfire but you never know.

Excel

Hey thanks for the quick reply canucklehead but the problem is there is no one around where i live that can read the codes.

I was looking for a code reader but couldnt work out if any OBD1 OR 2 scan tool would work or if it has to be Chevy specific and the ones i found were sold in the USA and didnt want the hassle if i was sent the wrong reader.

Info for parts etc for these vehicles seems very hard to find here for some reason.

canucklehead

Vauxhaul dealer no help? I thought maybe the same system. Most code readers work on a huge array of makes and models. Might be worth a few phone calls.
Pretty sure its odb2

Excel

I did think about a Vauxhall dealer tbh, il give them a call but if anyone can recommend a code reader that would be great too

Excel

Just got off the phone with the Vauxhall dealer, they giggled and said they only dealt with UK spec Chevy cars..........

I know the codes should be read but once your moving/cruising it does hold its speed well.

Do you think its worth changing the plug leads, dizzy cap and rotor arm and fuel filter as these seem to have been on forever and there is a slight damp patch on the fuel filter.

The previous owner barely used it and he said he never had it serviced in the 5 years he owned it.

Edit:-
Forgot to add, the truck has only covered 49000 mls

greenfire

I say do the full tune up on it. Plugs, wires, filters, etc.

canucklehead

There are too many sensors to guess at. Throttle position, camshaft position, mass airflow, etc. Without a code reader you are throwing darts in the dark.
Too bad you are not getting help. Maybe a smaller shop can try their diagnostic machine. Tons of cars use the odb 2 system. If not, then you can buy a hand held reader online. Might be worth the investment. Just watch as some require you to pay for the software updates and so on.
I lived in England for a year and a half and saw lots of chevy full size trucks around. There must be a dealer somewhere you can contact for some service advice.
good luck.

Excel

Hi guys,

Thanks for the advice, i went a got a handheld reader, just a cheap one (£20) that actually worked and read the codes which surprised me!

The codes i retrieved are as follows.......

P0101 Mass or volume air flow
P0171 Lean mixture bank 1
P0174 Lean mixture bank 2
P0300 Multiple misfire
P0430 Catalyst system efficiency below spec bank 2

The txt after the actual codes given are a bit vague because i just jotted them down quickly but you get the idea.

Im guessing the ''lean'' errors are because it also runs on LPG gas most of the time?

I have already fitted new spark plugs so i guess new leads, cap and rotor would be next and also a new fuel filter.

What do you guys think?

Thanks in advance

Excel

WOW 305 views and only 2 helped LOL Thanks canucklehead and greenfire

Just posting to say i have now sorted the problem and hope others may find this topic of some use.

I suspected the MAF so today i removed it, cleaned the probes with brake cleaner and cotton buds, and the inside of the MAF unit, cleaned the connectors with brake cleaner put it back together and it ran much better.

No warning lights came on and its back on power so just goes to show how one component failure can bring up so many error codes as it affects everything else in line.

Cheers again