Hello All,

I searched the archives and didn't find what I needed. I have a 1993 850, with 151,000 miles. The engine has developed a intermittent engine hesitation under load which is more pronounced going up hill. I haven't ruled out wether it is fuel related or ignition? I replaced the fuel filter and pulled the fuel pump and inspected the inlet filter and it was clean. I next moved onto check for vacuum leaks. I found and repaired a vacuum leak for the fuel pressure regulator, wasn't it. I temoraraly plugged the return side of the fuel pressure regualtor to rule out it was fauty, wasn't it. I inspected and cleaned the thottle body (two small taps and butterfly) and checked the throttle position potentiometer, all good.

The plugs were changed recently when I replaced the timming belt. Car is still drivable but is not acceptable. I do not have an engine code to give me a hint on what the problem could be.

Any help or guidence would be greatly appreciated.

Thanks!

 

Look at the cap rotor and wires.If they are old that is my guess on what is bad.

 

Thanks for the prompt reply Tech. I didn't think it would be the wires or cap because the engine miss would be present through the entire rpm band wether the engine was being laded or not loaded. The hesitation I am seeing is more pronounced when the engine is under load. I was leaning more towards fuel or vacuum.

At idle, I get around 20" of vacuum. When I blip the thottle, it will quickly drop to around 5" then return to 20".
I know of a good 1995 850 in a junkyard (was mine before my daughter totaled it, no injuries to her) that I can grab the spark plug wires and cap from and rule that out.

I was also thinking about hooking up an external fuel pressure gauge and vacuum gauge and monitor the reading when the symptoms are present.

John

 

Could also be a bad coil.

 

Might be the coil. I did observe that a faint ticking sound near the coil. I could not see any arcing but I thought the noise was abnormal. I'll grab the coil too from my old car. I'll let you know what I find. Thanks!

 

Look by where the center meets the metal bracket and look for burnt marks. From it arcking.

 

Problem is fixed. I went to the junk yard and put the good known coil from my totaled 95 850 in, wasn't it. Swapped out the wires, wasn't it. The owner of the junkyard who let me swap all these parts for free told me about a trip he took with his RV and his engine developed symptoms the same as mine. He replaced wires, cap, rotor, coil, and the problem still was there. He then swapped out the plugs and the problem was gone. Hmmmmm, could it be? When I pulled out the plugs, all 5 looked texbook perfect and looked identical. Swappped them out with a fresh set anyway and the hesitation under load problem was gone. The carbon core on one of the plugs must have been cracked? The plugs only had about 10,000 miles on them.

Total cost of repair was $9.

Money saved by diagnosing the problem.

$140 - not buying a new coil
$50 - not buying new set of wires
$30 - not buying a new cap
$15 - not buying a new rotor
---------------------------------------
$235 total

Now to tackle the AC leak.

Thanks for the help!

 

Thanks for the update Im glad it is fixed.

Keep us posted on the A/C.