No. 4222Anonymous 5th September 2018 Wednesday 8:59 pm4222Car intermittently "coughs"
HI lads,
Having a very strange problem with my 99 Celica 1.8 7A-FE.
The engine has a well-known issue with drinking oil, so I topped it up a couple of weeks ago. I mis-measured by about 100ml or so, meaning that the level ended up going to just cover the "F" marker on the dipstick; I consulted a mechanic who said it shouldn't be an issue - the oil level drops below full when the engine is started, indicating that it should be nowhere near the crankshaft.
Driving it a couple of days later, on the motorway, the car "stuttered", losing revs and engine braking for about half a second; this happened twice in quick succession before returning to normal.
I couldn't re-create the issue, and the mechanic said that wouldn't be a symptom of oil issues, anyway, so I went on driving it.
I had no issues for about a week, driving it about 200 miles in that time, until today. It did the exact same thing again but about 5 - 10 times over about a minute. before again returning to normal.
Any ideas what this might be? Dirt in the fuel? Failing spark plugs/wires? I'm waiting for it to cool down now to check the oil again.
When I had an old Yaris, I tried to fix an intermittent engine fault code by replacing the MAF sensor. The sensor was faulty and it caused a problem that sounds similar to the problem you're having.
I think what was happening was that the sensor was intermittently failing giving a bad reading, which forced the ECU into limp mode for a few moments until it works out that the reading is OK again.
The celica uses the exact same model of MAF as the yaris.
Mine was a more serious fault which was probably a bad connection making it fail completely for a few seconds and switching the engine warning light on. I expect that if your's is just not functioning properly due to a build up of dirt it could result in a short stutter like you describe.
A simple fix might be to take the sensor out and give it a clean using a can of electric solvent cleaner, clean both the electric contacts, and the sensor part (touching it isn't recommended). If that doesn't work, I would guess that the sensor isn't to blame. You can replace it easily with a new one, but the cheap aftermarket ones aren't worth the risk of them being FOA, and the genuine (Denso) ones are over £100.
>>4223 I hadn't thought of that. I'll look for it tomorrow and see. Unfortunately, it only has OBD I so the EML will pretty much never come on, and not give me much info if it ever does.
I'll clean the air intake too and change the air filter just in case.
Not at all helpful, but I have a curious electronic problem whereby my heater turns off and on depending on what the most recent pedal to have been pressed is. If I hit the brake it turns off, if I hit the accelerator it turns on.
>>4225 When I was young my mum had a car that was plagued by (at the time rather unamusing) faults. The most memorable was when, by some quirk of the wiring, the horn would sound continuously when the steering wheel was turned too far, ie every time while cornering.
I've put a new air filter in, cleaned the intake (it builds up with carbon causing the throttle to stick closed until you like "stamp" on it after it gets cold and has done since before I got the car), checked the pipe, checked any and all vac lines I can see, dropped part of the under skirt to check for any deposited fluids, sat there manually operating the throttle to see what happened, put a brick on the throttle and watched for smoke.
Fucking nothing, and it's so intermittent, so like it's been suggested before it's likely electrical, which even in a car as simple as this may be a death sentence.
Fuark. I'll book it in for a service (I don't have the kit or space to do stuff like check the spark plugs or a full oil change at the moment) and hope for the best. I have to drive it 55 miles tomorrow so I'll hope it's having a good day.