Driving Across Country - Hesitation / Power Cutting Out

[yacob555]

Just bought a '79 320i and driving home, still have ~1000 miles left.

Car has had an issue of a slight sputter between 2-3k RPM, especially going up hill. Issue seems to have gotten worse after hours of highway driving and then slowing down to 20-40ish. Seems to be getting worse as the trip continues. Not sure if that's just post-highway driving or not.

Has been driving beautifully on the interstate 3k+ RPM. Absolutely perfect.

Any ideas what the issue could be, and if there's any quick diagnosis / fix while on the road?

Really appreciate any thoughts - would like to get on top of it in case it becomes an issue completing the trip.

Previous owner recently cleaned the fuel tanks, took apart and cleaned the system pressure regulator "warm up," cleared all fuel lines, fuel pump, replaced fuel filter and gaskets, hose between tanks.

Thanks!

[pofo]

I would check the filter. He may have cleaned it but these cars are so old and especially if the car sat at all the tanks are prone to rust. unless he coated the inside of the tanks to seal the rust, I would say it's a good start.

[Beam318ti]

Agree with what Pofo said. This would not be easy to do while on the road but when you get to your destination, I would change the filter and see if that resolves the issue. If the car has been sitting for a while, the injectors may need to get cleaned/changed as well. Sounds like a fuel delivery issue.

[yacob555]

Thank you guys. He said they dropped the tanks and had them professionally cleaned and replaced the fuel filter. I do have a 2nd one with me if needed.

it’s odd to me that it’s totally fine at highway speed/rpm. Does that point to a particular issue?

[yacob555]

It’s VERY rough under 4K, beautiful above. Does that point to anything?

Idle is ok, but perfect but better.

Thanks

[OLD MAN]

Cap rotor wires and plugs - basically tune up if it has not had one for awhile. Adam our son had a Miata that was doing this. We were thinking something with the fuel system, turns out it was the plug wires. Car had electronic ignition, new set of wires = new engine or so.

[yacob555]

Cap rotor wires and plugs - basically tune up if it has not had one for awhile. Adam our son had a Miata that was doing this. We were thinking something with the fuel system, turns out it was the plug wires. Car had electronic ignition, new set of wires = new engine or so.

Coil wires going into the plugs are pretty wobbly. Is that normal?

Curious if coil issues would show up strongly at low rpm/under load but not much at all over 5k rpm?

Appreciate the help

[epmedia]

Just something else to check... If the little cam inside the ignition distributor in not smooth/polished/greased - that pad on the ignition points will wear out faster than usual and you will lose some gap on the contact points. Maybe check/reset the points gap, If point contacts are pitted, consider new ones. Make sure the capacitor wire has good connection too.

[yacob555]

Didn’t make it :/

Hesitation crept into the 4K rpm range and within a couple hours lost oil pressure in Roanoke.

Gotta figure out how to get it towed home or fixed there and driven back (to Philly).

Appreciate the help along the way.

If anyone knows a good Indy in Roanoke.....

[Beam318ti]

I am sorry to hear that you didn't make it. It is always. A big risk/chance to take an old car on a long road trip if you don't really know it's maintenance history upfront or if the car has been sitting for awhile. Best is to get it towed home now so you could assess the damage and figure out the best course of action.

[yacob555]

I am sorry to hear that you didn't make it. It is always. A big risk/chance to take an old car on a long road trip if you don't really know it's maintenance history upfront or if the car has been sitting for awhile. Best is to get it towed home now so you could assess the damage and figure out the best course of action.

Yep it was a risk we were willing to take. Had some good owners but we drove it about 20x further than it had been driven in the past few years.

Getting shipping quotes or may consider getting it fixed in Roanoke and finishing the trip.

We’re just lucky we were walking distance to the airport to get a rental car, and got the last one.

[epmedia]

Are you able to tow it home with rental truck / trailer?

[yacob555]

Are you able to tow it home with rental truck / trailer?

It certainly could, it rolls perfectly well.

I don’t have any experience towing or the equipment, however.

Looks like Uhaul rental is $385 to tow, not a bad option

[Mike323i]

It's a 79. Does it not still have points/condenser in the distributor? Check the points and make sure they're opening/firing? Points are so rare anymore that I think we all forget about them. I know I did and got burned/stuck once similarly. Such a simple fix, too.

- - - Updated - - -

I'll second the "check the points" recommendation. It's a 79. Unless someone did a Pertronix conversino, it should still have points/condenser in the distributor, make sure they're opening/firing. Points are so rare anymore that I think we all forget about them. I know I did and got burned/stuck once similarly. Such a simple fix, too. And the symptoms are similar.

[yacob555]

It's a 79. Does it not still have points/condenser in the distributor? Check the points and make sure they're opening/firing? Points are so rare anymore that I think we all forget about them. I know I did and got burned/stuck once similarly. Such a simple fix, too.

- - - Updated - - -

I'll second the "check the points" recommendation. It's a 79. Unless someone did a Pertronix conversino, it should still have points/condenser in the distributor, make sure they're opening/firing. Points are so rare anymore that I think we all forget about them. I know I did and got burned/stuck once similarly. Such a simple fix, too. And the symptoms are similar.

Damn! I wish I'd known this when I was on the road. It's currently in the shop in Roanoke (I'm in Philly). I'll give them a heads up to check that out, though.

After a while, it also lost oil pressure - likely unrelated. So, there's that too.

[yacob555]

Just for posterity, the sputtering/hesitation issue was a distributor condensor. Easy fix. Too bad the oil pressure dropped and created a knock.