Incomplete Shifting Through Gears

[Chacheska]

I have a '94 Metro with 77,600 miles. It's a 1.0 3 cyl 5 speed. Once every 5 or 6 times I get in the car to drive it, it will get about halfway through first gear then suddenly stop accelerating and the car will jerk. If I shift into second the engine lugs from the low rpm's and will get about halfway through second, stop accelerating and jerk again. This wlll happen all the way through the gears. If I take my foot off the accelerator in any of the gears the trans will engage when the rpm's drop but the same thing happens when I try to accelerate. If I try to force it to accelerate when it bogs down it just starts jerking. Now here's the key.... if I stop the car for a couple of minutes and restart, the problem disappears! If the problem isn't there when I first take of it will never happen once the car is running. It only happens when the car has been shut off and restarted at some point. Doesn't matter if the car is hot or cold. Again, it only happens about once every 6 or 7 times although once it happened twice in a row. The engine light came on the first time it did it but I don't have a code reader for a '94 and even Autozone couldn't pull a code from it. The only other thing I see is a rotted out muffler. Someone suggested it may be a clogged CAT converter. Whataya think? Back pressure problem?

[Metro Mighty Mouse]

sounds reasonable, soak the exhaust bolts in penetrating lube and unbolt the cat and see what happens.

[Chacheska]

Thanks. Nobody else seems to have any idea what it could be so I have nothing to lose. The key to what's wrong is the fact that shutting the engine off and restarting it cures the problem for awhile. That almost makes me think it's something electrical that's resetting something else.

[Metro Mighty Mouse]

it's going to be the cat or fuel supply most likely. when you shut it off some of the loose garbage in the cat could fall and open up passages. A weak fuel circuit, (fuel pump or supply voltage or pressure regulator), is actually more likely. shutting it off and turning it back on cycles the fuel pump, which may have a weak spot in it's electrical motor, this gets it going again. or you could be resetting the signal from the pressure regulator etc. It does sound like a fuel starvation issue, more demand causes the problem. Next time it happens you might see if you can get it to happen in neutral by holding it at a the upper range of the rpm scale for a while. You will be able to get more rpms because there is no load but you should be able to recreate the problem. Also getting the front wheels off the ground (safely) and that will reduce the load and should allow you to check things while the issue is occuring.

good luck!

[Chacheska]

O.K., I'll try that. What would you think the related trouble code would be and how do I access it? I assume it will be a emissions related code and I'll probably have to use the paper clip trick to get it. Thanks very much!

[Metro Mighty Mouse]

do a search on trouble codes in this forum and you should get all the information you need as there have been several good explanations in the time I have been on here. You may not get a code depending on what the sensors feed back to the ECU. OBD1 doesn't have a wealth of information, just a clue here and there. Pull any codes you get and post them here, someone should be able to give you an idea what to look for.

[Chacheska]

Thanks. I downloaded OBD1 codes off another site and my '94 shop manual also lists them. My problem is figuring out how to get them from the receptacle under the dash. Someone told me you can get it by using a paper clip and jumping two of the connectors. I think they were #1 and #2 but I'm not sure at this point. I appreciate your time.

[Metro Mighty Mouse]

on my 95 you put a spare fuse in the diagnostic slot in the fuse block under the dash. I am not positive where yours is located but I would start there.

[DOCTORBILL]

I had something somewhat similar happen to me - with several cars!

My threads in this forum are about similar problems which finally
devolved into the engine not running. I'm in the process of trying to
be Sherlock Holms and figure out what the F**k is going on!

Here it is - Have you had the fuel filter changed ever?

A nearly completely plugged fuel filter (I'm told gasoline is full of
crap!) will completely plug up during a driving session and when you
kill the engine, the crap will fall way from the filter and allow one to
start up and run the engine again - maybe w/o ANY PROBLEM for
that session and then plug up again the next time - i.e.
intermittant problem.

Just a suggestion... A 'semi-inexpensive' thing to try.

DoctorBill

[Chacheska]

Thanks for some good suggestions. I'm supposed to get notifiactions when someone posts an answer to my question but didn't get one for either of the last two posts so I apologize for not getting back to you guys and thanking you. I never considered the gas filter. My guess is that it wouldn't cause the stopping of acceleration at the same point in each gear. BUT ..... it wouldn't hurt to change the filter in any case. I have another '94 with 147,000. I bought it with 101,000 and have never changed that filter because the fuel lines look weak. I'm betting it will spring a leak when I try to change it. Thanks, guys!

[Chacheska]

Thanks for some good suggestions. I'm supposed to get notifications when someone posts an answer to my question but didn't get one for either of the last two posts so I apologize for not getting back to you guys and thanking you. I never considered the gas filter. My guess is that it wouldn't cause the stopping of acceleration at the same point in each gear. BUT ..... it wouldn't hurt to change the filter in any case. I have another '94 with 147,000. I bought it with 101,000 and have never changed that filter because the fuel lines look weak. I'm betting it will spring a leak when I try to change it. Now that you mention it, I do remember reading something about that extra fuse to check the codes. Thanks, guys!