been at it way to long

4rdwhln

Registered User
Hey There, I have an 89 cougar super coupe and it is sick. I have been chasing this problem for several years of and on. My car sits under a cover 90 percent of the time and is my on going project. I have replaced the front suspension every part of the brake system, most of the hoses under the hood including power steering and ac,the igy mod and all sensors except knock. I have performed the 20 or so tests involved in diagnosing the pressure switch on the side of the abs unit. When we had the dash out I replaced the evaporator core and heater core. I have also installed headers and built the system to the back with magnaflow and flowmaster parts. and it sounds awesome. but for the life of me I cant get any more than 15 lbs vac at idle,and i have a miss or something when ya get on it. I have pulled codes and performed all the tests. first it was code 49 spout wire prob. pulled harness tested everything u could imagine at least 3 times ran tests at computer harness as well all checks good. Then i got codes saying knock sensor on a friends scanner.took it home and located sensor marked balancer so u could see timing marks and started testing again.. everything passes and timing was right on spec all thru the tests.. take it out and jump on it and she falls on her face...miss miss miss....should mention new belden wires and autolite xp plugs as well less than 1000 miles on most of it. Any ideas? Hope someone out there has been there done that and can help out.
 
15 pounds of vacuum is on the low side while in park. IC tubes are the typical main offenders. I would say you should pull a page from the Dave Dalke book and get a smoke test performed from a shop that has this equipment so that you may determine where your vacuum leak is exactly. From there you can begin to trouble shoot with more accuracy if you still experience drivability concerns.
 
I had a problem at a shootout where it would do sorta the same thing pop, hesitate, cut out when I got on it and it turned out to be a cracked spark plug. Apparently I bumped one putting the headers on trying install them because I installed the plugs before, trying to make it easy.

Check your plugs very carefully. This doesn't have anything to do with a low vacuum reading, but could help the popping.

Smitty
 
Double check firing order. Haynes and Chilton manuals are wrong. They usually have 5 and 6 reversed.

Here is the right firing order:

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Thanks for the info

I was wondering about a plug issue. and will recheck the wires and plugs. Hope to find a mechanic with a smoke machine and go from there..I have been using pipe sealant on the intercooler tubes,as felpro,s o rings are a joke and i cant find the original sealing tape..the pipe sealant works awesome i might add. no oil coming out at the joints and it would for sure if it was leaking.Not much in the system but a little always runs out when the joint at the bottom of the intercooler is opened up.
 
15 pounds of vacuum is on the low side while in park. IC tubes are the typical main offenders. I would say you should pull a page from the Dave Dalke book and get a smoke test performed from a shop that has this equipment so that you may determine where your vacuum leak is exactly. From there you can begin to trouble shoot with more accuracy if you still experience drivability concerns.

For a high-mileage motor, 15 inches of vacuum is not all that bad. In my opinion.
 
Not sure if you have replaced the coilpack itself. I had the same problem, bucked and fell on its face only on hard throttle. Checked plugs and wires, we're fine. Replaced the coilpack and it was as good as new.

Chris
 
Dude. I see what your saying. But having lived this exact problem like a zillion times I would suggest you take a couple hours to take the windscreen cowl off and zip tie every single vac line. Find every single one that is supposed to be there. Then pull and regap with tender care each plug making a mad effort to get the wire secured to the plug and the spark plugs inserted "just right". Plugs wires bro. Plugs and wires.

Mike
 
Dude. I see what your saying. But having lived this exact problem like a zillion times I would suggest you take a couple hours to take the windscreen cowl off and zip tie every single vac line. Find every single one that is supposed to be there. Then pull and regap with tender care each plug making a mad effort to get the wire secured to the plug and the spark plugs inserted "just right". Plugs wires bro. Plugs and wires.

Mike

^^ This is good advice ^^
 
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