Strange engine activity?

Topic: Strange engine activity? (Read 3345 times) previous topic - next topic

Strange engine activity?

October 13, 2009, 04:25:43 PM

I finally managed to get my Cougar home. It's a 1987 Mercury Cougar XR7, factory 5.0 SO and all that jazz. The engine was pulled and replaced with a low mileage 5.0 from the same year car. Everything on the engine was replaced, Timing chain, plugs, plug wires, all the gaskets except head gaskets...etc. The only thing that wasn't messed with are the air/fuel electronics on the inkate manifold. Like the IAC, MAP sensor and TPS. All the vacuum lines are attached and the car runs very good....most of the time. However sometimes when I am out driving it will randomly start running rough. Almost like its running lean and almost dies. Then it will stop and continue running perfectly? Not sure what the cause of it is. Hopefully you guys can help me straighten this out. If you need anymore info let me know.

Peace,
Dan W.

Strange engine activity?

Reply #1 – October 13, 2009, 08:33:39 PM

Try replacing the MAP sensor, it could be going bad...

Strange engine activity?

Reply #2 – October 13, 2009, 08:40:28 PM

Better yet; pull codes so you're not just throwing parts at a problem that has not been diagnosed.

Strange engine activity?

Reply #3 – October 13, 2009, 08:45:03 PM

My Saturn started doing this after I filled up at a rural gas station. The tank was full of water. I drained a half gallon or so out of it...

Strange engine activity?

Reply #4 – October 13, 2009, 09:58:50 PM

Im not too concerned about spending money on it. The car has been sitting for a few years so Im sure all those bits need to be replaced anyway. I'll pick up that MAP sensor tomorrow. BTW I will try to get some pics of her soon too, Thanks.

Strange engine activity?

Reply #5 – October 14, 2009, 04:12:13 AM

I haven't had a single map sensor go on me yet, at there near $80 new. I would pull codes. Your just gonna waste time and money. Also, what kind of shape are the vacuum lines in?

Strange engine activity?

Reply #6 – October 14, 2009, 07:48:48 AM

Quote from: Haystack;294760

I haven't had a single map sensor go on me yet, at there near $80 new. I would pull codes. Your just gonna waste time and money. Also, what kind of shape are the vacuum lines in?

X2... Never seen a bad MAP sensor...

Strange engine activity?

Reply #7 – October 14, 2009, 11:43:38 AM

i had a bad one once......had a broke motor mount and got on it hard enough to break the nipple off....my hose is connected straight to the engine as i am not running the vacuum tree....

Strange engine activity?

Reply #8 – October 14, 2009, 03:41:49 PM

As per recommendation I checked all the vacuum lines and they look fine. I also tried disconnecting the MAP sensor, but that made things worse so I don't think its that. Then I tried to pull codes only to find my check engine light doesn't work. Running out of things to try, I unplugged the IAC. After that I took her around town for a bit and she never once bogged down or acted like she was gonna die. Any thoughts on this?

Strange engine activity?

Reply #9 – October 14, 2009, 04:07:35 PM

Many stored codes will NOT trip the check engine light -- even when it is working as it should.
Just a suggestion: Invest in a vacuum gauge. It'll be a wisely spent $25.

Strange engine activity?

Reply #10 – October 14, 2009, 05:02:44 PM

Quote from: Dougy_Fresh;294785

got on it hard enough to break the nipple off......

Ummmm.....:burnout:

Strange engine activity?

Reply #11 – October 14, 2009, 05:04:15 PM

Quote from: Roehm;294800

I unplugged the IAC. After that I took her around town for a bit and she never once bogged down or acted like she was gonna die. Any thoughts on this?

Take the iac off and clean it well with carb cleaner and put a new mounting gasket back on it ?

Strange engine activity?

Reply #12 – October 14, 2009, 05:49:15 PM

http://therangerstation.com/tech_library/OBD_I.html
http://therangerstation.com/tech_library/2digitcodes.html

All you need is a paper clip and a test light, or if your check engine light works, you can do that.

Strange engine activity?

Reply #13 – October 14, 2009, 09:02:55 PM

I grabbed a test light before I got home. I'll check it tomorrow and let ya'll know whats up. Thanks

Strange engine activity?

Reply #14 – October 15, 2009, 12:35:28 AM

were all here to help when it is needed.