7 replies to this topic

[Jamie_hail]

Right - been through EVERYTHING now! Going insane!

The car is a 97 MPI, it starts fine, but seems to get hot very quickly! Running can be very lumpy, and the revs will occasionally go anything between 800 and 2000 by itself at idle, normally sorted by a rev of the throttle. Idle is fine and the car doesn't smoke atall. Plugs are a little black, so maybe running rich.

The problem only seems to be under load - I can sit in neutral and the car will rev cleanly all the way to 8k, put it in gear and try to accelerate when moving, and she will backfire, jerk and have next to no power, enough to maybe creep at about five mph or so... This even occurs when you hold the revs at 5k and let the clutch out slowly - the revs will drop and she will back fire like *******, and again, creep and jerk. The only way to get her to go is let off the revs completely once moving, let the clutch right out, then put your foot on and off the throttle a few times...

I've tried everything that I've thought of, so I'm going to start from scratch now I know a bit more about sensor locations, lines and everything...

Don't know when the fuel filter was last changed, so should I try that, does it sound like a dirty filter could cause this, poor fuelling? Doesn't explain the richness though. Alternator doesn't seem to be charging the car at idle - the voltage on the fresh battery was 13.4 volts, but that dropped down to 10.6 after sitting listening to music with the engine running... Although I do have a 1000 watt system in the car, so it's not surprising... Voltage sits about 11.8 volts with the stereo off.

Previous said the back box was blowing, but I cant find any holes or cracks in the silencer, but it shall be replaced as a precaution when I get some cash...

Could be vaccuum lines leaking, but I've wrapped existing lines in super sticky tape to just get a makeshift seal, and not the slightest difference... I have a vaccuum guage in the car though, so should I check what numbers I'm getting under different circumstances? Acceleration, idle, revving in neutral ect? Does anybody know what figures I should be getting?

How do I check the tappet clearences? What should they be set to, and how do I set them?

Any sensors that I could disconnect to give the limp home value, see if it runs better? Or what should I at least check and clean up?

As far as I know, the only modifications to the engine are an overbore, the K&N in the photo below, and the swift duplex timing gear...

[liam_italian]

The backfire is no doubt being caused by fuel that has not detonated in a cylinder, and once it has traveled out of the cylinder into the exhaust manifold it's detonating.

Firstly I would do a compression test, anything over 180 PSI/12BAR is good, although the figure needs to be similar for all 4 cylinders. If it's not then your headgasket could be on the way out.

Secondly make sure all spark plugs are working, you can do this by removing one with the ht lead still attached and hold it with insulated pliers against the engine block and get someone to turn the engine over, if there is a spark then it's ok. Do this for all four. It's possible one is not working causing a misfire. If this is the case try swapping the spark plug with another just incase it's the HT leads

Thirdly remove the (IACV) or stepper motor as it's commonly known and give it a good clean.

If none of the above identify the problem then it could be the injector(s) etc.

[Jamie_hail]

I'll get myself a compression tester tomorrow, see what figures we get... Should it be done wet or dry? Hot or cold?
I'll replace all the plugs again on the off chance one of the fresh plugs were dodgy, might as well do the leads at the same time anyway just to be on the safe side! I should steer clear of the 'universal' type, shouldn't I? What are the best HT leads I can get?

Will have the stepper motor off either tomorrow or the next day... these need reset when put back on the car, don't they?

Previous owner had the injectors ultrasonically cleaned, as far as I'm aware... If none of the above seem to help the running of the car, I'll do the valve clearances again, and then check the cam timing...
If not - anybody want an Mpi engine and tranny, front subframe, and two wiring looms?

[Guess-Works.com]

Got this funny deja vu feeling....

Is this the car per-chance ? http://www.theminifo...howtopic=190613

[Jamie_hail]

Got this funny deja vu feeling....

Is this the car per-chance ? http://www.theminifo...howtopic=190613

It sure is - the running problems didn't bother me when buying it... As the original plan was to vtec it (and it still is) But due to the lack of cash, I'd like to get the original motor running right for a while!

[Guess-Works.com]

I put in an offer on the car, which was obviously not accepted, but was at such a level that the engine would just have been taken out and replaced in it's entirety, loom, sensors and ecu.

Think that is your best, cheapest and quickest option.

[Jamie_hail]

I put in an offer on the car, which was obviously not accepted, but was at such a level that the engine would just have been taken out and replaced in it's entirety, loom, sensors and ecu.

Think that is your best, cheapest and quickest option.

Yeah! Got her for just under a grand, like I said - the plan is to fit a B16B engine on ultrik subframe, but until then, it would of been nice to get the mpi block working!

[jamesmpi]

I think what guess works is suggesting is that the previous owner spent a lot of time (and I assume money) trying to fix the exact problem the you are describing and by the looks of it he or she didn't succeed. So as suggested your best option in the long run is to strip everything and give it a detailed inspection.