What now? STILL running rough

GOODHEART99362

MEMBER
MERCURY SABLE

91 mercury sable/125k/3.8l--after complete tune up still rough, 3 scans gave me diff. Things which I replaced--o2 sensors, heat temp sensor, etc. Checked 4 vacuum leaks, cleaned egr valve, cylinders are EVEN. Changed filters, wires, plugs, pc valve. Ran fuel cleaner thru gas at least 3 times now. Engine light comes on only sometimes but goes out after about 10 sec.I suspect one thing--bad spark plug wires, which would very much upset me-supposed to be lifetime and after all this money and work it turns out THIS? What else COULD it be? Tired of getting ripped off and the results from it--see how it snowballed?

4 Replies

MERLIN2021

MECHANIC
17,250 POSTS

On 91's it's usually the manifold absolut pressure sensor. MAP!

Was this

answer

helpful?

Yes

No

Sunday, April 15th, 2007 AT 8:37 AM

GOODHEART99362

MEMBER
3 POSTS

________________________________________
After reading some of the answers I thought of that, but why didn't that show up on the scans? I don't want to by another part and have the same problem. How can I test for it? It's easier to test the wires--simple things first. I have a manual but it's basically the same thing: "it could be this or this or this". I work on cars myself and maybe that's why they are taking advantage of me (female). Also want to share info for huge savings on parts: PartsAmerica. Com. You look up your part and they send you to a local affiliate, where you get up to or even more than a 50% discount. The site tells you if it's in stock, and the "affiliate" can't jerk you around. Only on a special order--like a custom/import part--can they charge you a regular price. Well thanx for the suggestion. Maybe I'm getting somewhere. Why the fuk did they put computers in cars?

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

Monday, April 16th, 2007 AT 1:35 PM

MERLIN2021

MECHANIC
17,250 POSTS

Yes if you have a code reader it may give you a fault code for the MAP The other thing you can check for is vacuum leaks, get a can of spray gumout, spray around vacuum hoses and intake manifold, see if the engine changes speed. If it does you've found a leak.

Was this

answer

helpful?

Yes

No

Tuesday, April 17th, 2007 AT 3:57 AM

GOODHEART99362

MEMBER
3 POSTS

__________________________________________
I had checked for vacuum leaks but will try the gumout thing. Don't have a code reader--have enuf useless tools! A MAp sensor will cost me about $100-even at a discount price (PartsAmerica) so thanx for the tip. Will keep you updated until I find the problem. This should be a really good engine when I'm done! My last old beater won 2nd in a Demo Derby-it had a V-6 in it too. P.S. Cool name. That was my uncle's name too, only spelled Merlyn. (German)

Was this

answer

helpful?

Yes

No

Tuesday, April 17th, 2007 AT 1:42 PM