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Cedar City Mechanic Recommendation? - Fuel Supply Problems / Stranded!

Discussion in 'BMW' started by Jay Pollard, Jun 27, 2010.

    Jay Pollard guest

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    Not sure if this is the correct forum for this post, but my father recommended that I use his account to seek advice on a problem I'm encountering.

    Right now I'm stranded with my girlfriend in Cedar City, Utah. We're trying to drive cross country to Saratoga Springs New York with most of our belongings in my 1987 325is. We were driving up UT-14E and it started to hesitate. I was in 4th gear around 3000 RPM's and it felt like it was in cruise control and couldn't maintain speed up the hill and would sort of hesitate. At first I thought the clutch was slipping. So I turned around and headed back down the mountain road into Cedar City. At one point I stepped on the gas and the car stalled. I tried to re-start it by turning the key but couldn't get it to start, so I jumped it in 3rd gear and got it going again. Towards the bottom of the hill I tried giving it gas again because I was really slowing down and it responded normally and drove fine. So after consulting with my father we've agreed it's some sort of fuel supply issue. Unfortunately I wasn't able to find a garage open on the weekend. So we're likely stuck here until Monday at the very least.

    Anyway, I'm hoping someone here could recommend a mechanic and/or give any advice on what might be going on here. The car is high mileage but well cared for. It's also extremely heavily laden; roof top carrier and full passenger compartment and truck. It's also pretty hot here right now and we were going up a 7% mountain grade, probably around 40mph when we started having issues.

    Thanks for any help at all and feel free to email me at jono.pollard@gmail.com or calling at 415-238-4435. Thanks!
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    lkchris

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    Jay Pollard guest

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    update...

    Ok, so after much discussion it seems I have made a foolish mistake and this may be the cause of my problems. My 325is has a performance chip in it, and apparently I'm supposed to only use 91 octane fuel. I've had the car for two and a half years now and have only ever used 87 octane. Here in Utah though "regular unleaded" is 85 octane. And I've put two tanks of it in now. Right now I'm at about 3/4 full and that's what I was using when it started to sputter and stall. Anyone think that might be the only problem here? Draining this 85 octane fuel out and re-filling with 91 might solve the problem?

    Thanks for any advice.

    Jono
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    steven s

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    I would add an octane booster to the gas.
    I would expect pinging though.
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    CRKrieger

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    No. I doubt it. Do you not carry the OEM chip with the car?

    Jay Pollard guest

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    I do have the OEM chip with me, but I'm worried that I'll bend a pin and mess everything up if I start messing around with it. Why wouldn't draining the fuel out and replacing it with higher octane solve the problem?
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    CRKrieger

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    Because, honestly, I don't think that's your problem, but if it is, changing the chip would solve it.

    Jay Pollard guest

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    Made it over the first pass...

    Ok,
    So another update. I had the fuel filter replaced this morning and topped off with 91. I made it fine over the first pass but on the second pass had trouble. It sputtered out and stalled about a mile from the 9600' summit. I managed to get it running again and over the summit and made it the rest of the way to my next destination in New Mexico. Hopefully I won't be going over any more summits but I'm still wondering about the problem. I think it tends to be more likely to happen when it's hotter out, both times it happened it was pretty hot out. Also, this time I did notice the engine pinging whenever it was about to stutter or had just stuttered.

    Jono
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    Zeichen311

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    From the symptoms you described, I wouldn't discount the possibility that the DME--really, that aftermarket chip--is simply straining to cope with the thinner air at high altitude. Higher octane fuel probably helped by allowing more timing advance, giving the engine more room to work before it started shutting down to protect itself. It sounds like the engine simply can't breathe: more properly, the control map can't cope efficiently with oxygen levels as low as 70-75% that of sea level. Heat is an additional factor because it further reduces air density, thus further reducing the available oxygen.

    Your engine has altitude sickness. Swap out the chip.
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    CRKrieger

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    That only happens in an engine with a knock sensor. The M20 doesn't have any ...
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    Zeichen311

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    Didn't know that about the M20, thanks. Given that, I'm not sure why the fuel change mattered, but let's leave that aside for the moment. How about a mass-air flow sensor--does it use that, or one of the older schemes based on indirect measurement (i.e., not air mass)? I'm unsure of the specific sensor and control systems in play here but you see what I'm getting at: A screwed-up fuel-air mixture because the computer does not have an accurate model of the available oxygen.

    Back in 2000, I drove a just-broken-in rental Civic over the Powder River Pass in Wyoming (el. 9,666 ft.) and well below the summit the poor thing was literally gasping for air. The engine sounded and felt terrible and power was off so much it could barely maintain speed (70 mph) up the grade, even at wide-open throttle. Once I descended below about 8,500' or so (rough guess, from memory) the car returned to normal. It wasn't until Jay mentioned a specific elevation that I made the connection. I was carrying only a modest amount of luggage (<150 lbs) whereas his car is fully laden, so the effects would be more pronounced.
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    lkchris

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    Fuel is lower octane in Utah because it's higher altitude.

    Your engine should see it that way and I wouldn't jump to assuming this is a problem.
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    CRKrieger

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    That M20 doesn't use a MAF sensor, it has an AFM (Air Flow Meter), just like the E28. It is hardly affected by altitude. That's why I think his problem is elsewhere. I emailed him the first day to check the fuel pressure regulator as well as the fuel pump(s). He hasn't done that. He decided it was the fuel octane rating and chased that - apparently not solving the problem. If you don't check the simple cheap stuff first, you can expect to throw a lot of money and parts at it before finding the problem.

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