Dear people who know more than me,

I recently purchased a 1992 Ranger, now with 72,000 miles.

The engine is the 2.3 litre 4 cylinder with 8 spark plugs.

The is no conventional distributor, nor coils. There are a pair of square blocks that I guess are electronic ignition units. Each feeds one set of 4 HT leads.

It didn't run right when first purchased. I returned to the seller and he believed that the catalytic converter was gummed. He replaced the converter with a straight through pipe.

This seemed to cure the rough running for a while, but it has recently returned, so it seems that the converter was not the real reason.

Symptoms are spluttering and pulsating exhaust note and a motor that's too easy to stall when taking up first gear (it's a manual gearbox).

Until today, the exhuast was blowing at the connection where the straight through pipe is clamped, but I don't believe that this is the reason for the rough running. Anyway, I used exhaust cement on it today.

Compression testing reveals these results :

1 - 150 psi
2 - 150 psi
3 - 120 psi
4 - 120 psi

I may be able to get a higher psi from 3 and 4 with a tighter connection. Anyway, compression looks to be OK.

I have replaced the spark plugs on the right side of the engine, plus the first plug on the left side. I have also replaced the HT leads that correspond to these spark plugs. I intend to get to the other 3 spark plugs on the left side but they are more difficult to reach.

Anyway, there's a complete set of new spark plugs and leads on the right.

The engine still feels like it's missing on one cylinder.

Do you have ideas for may be causing this problem ?

Thank you

Stark

 

What brand of plugs did you use. I would suggest Motorcraft plugs and wires. You are correct that the "square blocks" are the ignition coils for each bank of plugs.

Does the "Check Engine" light come on? Have you checked for trouble codes. If you don't have a scanning tool, AutoZone or Advanced Auto can read the codes for you (no charge) and tell what the codes mean. The computer is expecting a reading from an O2 sensor, which mounts on the cat, but you don't have one. As a result the computer doesn't know what the proper fuel mixture should be. This may be the source of your driveability problems.

 

you should not have 30 psi difference between highest and lowest readings. If there is then unless you pull the engine apart, no amount of work you do on the outside of it will make a lick of difference. It could be as small as just a head gasket, or a rebuild. Get a vacuum guage and plug it in direct to an intake manifold port. Go to How to Use and Interpret a Vacuum Gauge to find out how to interpret the readings.

PS - Never just replace one plug! And you can get a boss welded into the exhaust pipe to accept the O2 sensor. But check the vacuum guage first!

 

Pull the codes, or have them pulled for you. If you have a misfire, you should also have a stored code. Start there, before you make any decisions about what to spend your money on. It could be a lot of things, a code would narrow down the search a little.