Thanks in advance for your help, this is my first post but I've been lurking for a couple of years whenever I have a problem.

I'm going to try to be as thorough as possible so please bear with me. Over the Thanksgiving weekend my '94 940 (133K miles) had been sitting nice and cozy in our garage for about 3 days when I tried to crank it. It shuddered violently and wouldn't start, it just shook. I waited a minute and the same thing happened again only it was a little less violent without so much shaking. I opened the hood like I knew what I was doing and checked the oil and coolant levels. The oil was a little low so I put a quart in and tried to crank it again and it started up just like nothing had ever happened. I didn't give it another thought. Fast forward to 2 nights ago. I drove from work (about a 45 minute drive) straight to the grocery store. After getting back in the car it cranked just fine but as I was driving across the parking lot I had no acceleration and the car would intermittantly lurch forward like it was having spasms. I pulled over and sat for a few seconds in drive listening to the idle. The idle sounded completely normal. Then I pulled back out onto the road and every time I would give it gas it would lurch forward and then slow back down. Then it just started driving normally again. I thought it seemed like maybe my fuel injectors were dirty and it was misfiring so I planned to buy some techron in the morning. I forgot and drove to work as normal yesterday morning and then drove home. I parked the car in the garage and went inside to grab some clothes to run to the dry cleaner and when I cranked the car again 5 minutes later it started doing the lurching no power thing and driving uphill it was rediculous. I couldn't reach more than about 15 mph on a flat surface. I kept expecting it to get better but it didn't so I turned around a mile down the road and came back home. I was going to drive it straight to my mechanic this morning or as far as I could and have it towed the rest of the way if necessary. I made it about 45 minutes and as I was merging onto the interstate in rush hour traffic I accelerated and then lost power and the lurching began again. I managed to limp about 5 miles in the emergency lane to the exit my mechanic is on and lurch from one parking lot to the next until I got to his garage. He says he thinks it is either a restriction in the exhaust system or the air mass meter? He originally said it sounded like a gas pump problem which made sense to me since I only had about 1/8 of a tank. Any ideas? Anyone else have this problem?

To sum up:
• Except for very fist time it happened it starts up just fine and idles normally.
• Runs fine when starting from cold, only acts up when restarting a hot engine or after driving for a while.

• Lurches forward intermittantly as gas is pressed. No acceleration.

•1994 940 Turbo 133K, regular scheduled maintenance. One small oil leak from rear engine seal. Original turbo unit. Never had a really big problem. Never beeen in a wreck.

• No check engine light or any indicator light at all.

Thanks,

Josh

Thanks for all the info. I put in a bottle of Techron. I'll try to remember to do that every so often because I know I'm just too cheap to be able to resist that $1.19 Kroger gas. I don't have any pinging, so I guess I'm ok with the regular for now. I'm hoping to drive this car for another 100K at least, so I'm sure I'll be back with more questions for you guys! Thanks again.

Josh

Does the problem exist in all modes of power production (with boost and without)? Or one mode or the other? It sounds similar to a problem I had a few years ago when my 945T had about 135k on it. Turned out to be a hole in the intake hose between the intercooler and the throttle body (right by the connection w/the intercooler, on the bottom). It was invisible to a cursory visual inspection and hard to feel because of its proximity to the neck of the intercooler. It seemed to open up intermittently which is why it didn't always exhibit the power loss. I didn't find it until I actually removed the hose to clean the inside and found the mushy area deteriorated by oil. Wouldn't hurt to check it out before dropping $$$ on diagnosing it. It screwed up the AMM readings because it was allowing air to escape during boost and allowing extra air to be sucked in during non-boost.

Don't get me wrong, I'm not disagreeing w/your mechanic, just throwing out an option not yet covered. Let us know what you find...
--
Bob Kraushaar '94 945T, '91 940T(back from retirement), '88 240, '84 242Ti, '94 F-150, '88 300TE, '89 560 SL, '68 Shelby GT-500 KR

Well it turned out to be the main fuel pump. So I got it replaced and she's running like a top again. I drove around quite a bit last night to make sure and it seems to have solved the problem. My mechanic (who by the way is a great and honest guy, if you are in Atlanta on the northside you should bring your car to him, Europe Car, in Dunwoody off Chamblee Dunwoody and Mt. Vernon) said the old pump would only work erratically when he took it out to test it. It would stop and if he hit it with a hammer would start again. Is there any way I can avoid this happening again in the future? Does it matter that I never put premium unleaded in? I buy the cheapest gas I can find (usually Kroger gas), could that be hurting things?

Thanks for the help.

Josh

Dear Josh,

Good p.m. and may this find you well. To offset using low-cost gasoline, you might want to clean the fuel system every 1,500 miles or so. You can use Techron (a Chevron product). Be sure to get pure Techron (black bottle) and not products that say "with Techron", which have diluted Techron. You need full-strength.

Fuel systems need to be cleaned because gasoline is a chemical cocktail. It is a mixed bag of products distilled from crude oil.

All gasolines share basic characteristics, i.e., all 87 Octane fuels will ignite similarly and provide pretty much the same amount of energy. Howdver, some gasolines are richer than others in compounds that "plate" fuel system surfaces (e.g., fuel injector nozzles) with "varnishes" or "waxes".

It is because these compounds are present, that all gasolines have "detergents" added. These are not "detergents" in the laundry sense. These "detergents" keep "waxes" and "varnishes" from building-up on fuel system surfaces. Because crude oils vary a lot, the amount of detergent added may not be sufficient to prevent "wax" or "varnish" build-up. On a fuel injector, these deposits degrade the spray pattern and, in extreme cases, actually can clog an injector.


Higher grades of gasoline - e.g., premium - typically have more detergents in them.

Techron is a concentrated gasoline "detergent". A 12-ounce bottle can be bought at Wal-Mart and auto supply stores. It will treat up to 12 gallons of fuel. It should cost about $5.99. It should be added to the tank before you fill it.

It will remove build-ups that degrade performance. You might want to do two treatments back-to-back, rather than waiting to record 1,500 miles between each one.

As you know, fuel system components are pricey. A $6 bottle of Techron is low-cost preventive maintenance.


Yours,

spook

p.s. I used Techron in an '85GL (240) with 198K. The fuel system components - pumps, injectors, cold start regulator, etc. - are all original. Only the fuel filter has been changed (several times).

I live in Snellville. I'm glad you found the problem and have a good, honest mechanic. Isn't it a bear when you have to go out and hit the fuel pump with a hammer every few miles? I wouldn't worry too much about a repeat performance, my 940's each have over 175k and all pumps are still original. I'll keep my fingers crossed but my experience has been good with the things.

As far as the gas, use the lowest octane that the car does not ping with. If it pings, you will have decreased performance because the computer will automatically adjust the timing to compensate for the ping, this will decrease power production and therefore, performance. Using an octane that is too high will not hurt anything but your wallet, so try a tank of each grade and see what happens. I have found, the more mileage, the higher the octane necessary because of carbon buildup in the combustion chamber resulting in a higher compression ratio. I used to get along fine on dirt cheap regular unleaded but of late have had to move up to midgrade to keep from pinging. An occasional ping probably won't hurt anything but a steady diet will eat away at the piston and could eventually knock a hole in it. Not good.
--
Bob Kraushaar '94 945T, '91 940T(back from retirement), '88 240, '84 242Ti, '94 F-150, '88 300TE, '89 560 SL, '68 Shelby GT-500 KR