no power under load + backfires - fuel pressure? ignition? sensors/ecu?

My Gen 1 truck has the G63B 2.0 in it. On the fuel filler door there's a decal stipulating 97+ octane fuel but I bet every owner cheaped out on it and filled it with regular pump. It seems like a pretty exotic fuel to use in a 4 cylinder truck made in the mid 80's. This isn't a feedback operated carb and doesn't have an O2 sensor in the exhaust - Australian delivered trucks 'may' have a higher CR but I don't know/doubt it. I use the equivalent of premium in my Hyundai beater wagon. There is a definite difference in engine behaviour compared to regular pump (bearing in mind this is a 16v twin cam 2.0). It idles and runs smoother, has better throttle response, more torque and improved power all round. I have tried using 98 in it and it felt down on power and torque (not what I expected). It still idled and ran as smooth as 95. Only way to get the best performance out of your engine is to test different fuel and tune combos...

Ah yeah, US-market engines in general (esp. those still carbureted) often had a nerfed CR during that era to help meet tougher NOx smog standards; RoW models likely differed with a higher CR that may require higher octane.

Also, octane rating standards can differ by country, so that 97 RON octane in AU would be equivalent to about 91 (R+M/2) octane in the North American market.

...wonder what they did to bump CR's to the OEM engines :think:

It will be timing limited probably

thats the case on my nissan, its a JDM import so its running quite a lot more timing than the ones that went to the usa. Better fuel and giving them more timing gives the USA ones more power

retarding the timing reduces the dynamic compression ratio, so less pressure on the intake mix, so less preignition

Quote:

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Originally Posted by tortron

It will be timing limited probably

thats the case on my nissan, its a JDM import so its running quite a lot more timing than the ones that went to the usa. Better fuel and giving them more timing gives the USA ones more power

retarding the timing reduces the dynamic compression ratio, so less pressure on the intake mix, so less preignition

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Makes sense. It seemed like the plug gaps on US factory tune specifications were... generous. So retarding the timing and adding a big plug gap (1.1mm?) will seriously affect power output and make the requirement for higher octane fuel unnecessary.

OK so here are the factory tune specifications for Australian market G63B 2.0 optioned trucks -

13 deg BTDC+/-2 deg @ 700 rpm +/- 50 rpm

plug gap 0.7mm - 0.9mm

*and a link to a review of the lowest mileage L200 on earth - https://www.drivesection.com/reviews...xpress-review/

It's the base model. It has vinyl flooring and the small side storage boxes under the bench seat. No clock, AM radio only and no A/C.
And - it's perfect :green:

Quote:

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Originally Posted by geezer101

...wonder what they did to bump CR's to the OEM engines :think:

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Typically most mfrs. just used lower-compression pistons in their US-bound engine builds during that era.