Idle Problems

Topic: Idle Problems (Read 1008 times) previous topic - next topic

Idle Problems

May 01, 2007, 04:26:19 PM

I have an 88 Cougar 5.0L and since last year i have had a surging idle problem and i can not figure it out. My car will idle up and down and sometimes it quits. I was just wondering if anyone could tell me what to check. I already cleaned the IAC.
I since changed to a 5.0L HO and I still have the problems and I have another problem now when i am going about 50km an hour and i let of the gas especially going down hill the car itself surges. I had the car to a transimisson shop and he said it is not a transimission problem. I bought the kit for the mass air conversion from http://www.mass-air.com and installed it with the 5.0L HO engine so all the mass air stuff is new including the computer. I got the heads ported and i got a bigger cam the specs are .050 dur intake 212 exhaust 222, sae dur int. 389 exh. 299, cam lift int. .308 exh. 319, valve lift int .492 exh 510. This is just so you know what I am working with. Please any help will be greatly appreciated. Thanks.

Idle Problems

Reply #1 – May 01, 2007, 07:28:18 PM

Have you checked the TPS? EGR? The first thing that came to mind is a write-up I read on another site about the ten pin connectors, but it could be that it has nothing to do with it. It is worth a look into it.

http://fordfuelinjection.com/?p=85

Idle Problems

Reply #2 – May 02, 2007, 12:38:54 AM

Did you cahnge your MAP/BAP sensor? I had to change mine when I did the HO swap because of hot idle problems. It made a world of difference.

Idle Problems

Reply #3 – May 02, 2007, 06:06:31 PM

I just got the map sensor that was on my cougar. Which do i buy now? 1 for an 89-95 mustang?

Idle Problems

Reply #4 – May 02, 2007, 09:49:23 PM

Any Fox body mustang that was mass air. So just get one for like a 92 Mustang. Thats what i did. I hadnt thought about the map/bap cause you said it did it before the HO conversion. It did make my car run better after i changed mine.

Idle Problems

Reply #5 – May 03, 2007, 12:51:43 AM

Have you checked your exhaust especially the cats? My three cats on my 95 Cougar are clogged and it really messes with my idle but as long as I keep the RPMs high it runs smooth enough. When I am forced to stop it lopes a lot but it actually sounds like an older style muscle car but with an occassional pop. I also thought that I could of had a tranmission problem because of surging but that's normal when the transmission wants to shift into a higher gear but the lower RPMs messes with the engine when the exhaust is clogged.

Idle Problems

Reply #6 – May 03, 2007, 09:53:20 AM

Have you made sure the vacuum line to your MAP/BAP sensor is no longer connected? Also what are your lobe centers and lobe separation angle on that cam? That cam needs a little more idle RPM than the stock cam so that may have something to do with it as well. 50km/hr is about 30-31 MPH so with stock gearing you should be low ballin third gear (not too deep in the rev range 1200 or so RPM).

Check all vacuum hoses for cracks/holes and make sure they are connected (except the BAP/MAP hose) and see if you can find a known good BAP/MAP sensor from a yard or a friend and swap it in and see what happens.

You should also check for codes. I have a hunch you will get a lean air/fuel code with that cam as well. I say maybe because you're still ( I assume) running stock heads. With that cam and a vacuum leak I can almost guarantee a lean air/fuel code with stock 19 pound injectors at factory set pressure.

Idle Problems

Reply #7 – May 07, 2007, 05:21:37 PM

lobe ctrs are 107 intake 117 exhaust i just bought a new map sensor but the problem is still there. The heads are stock heads except that i got them ported. Another thing to note is I took off the pollution stuff. If my car is running lean what do i do to fix it. Thanks.

Idle Problems

Reply #8 – May 08, 2007, 08:24:10 AM

Your lobe centers equate to a 112* lobe separation angle which is OK for a mass air equipped car (It SHOULD have enough vacuum)

Again; have you checked for a vacuum leak? Did you plug the backs of the cylinder heads where the smog equipment ties in?

You're not running a breather on the valve cover, are you? That just creates a vacuum leak along with unmetered air.

If you have no vacuum leaks right as the car sits now and you get a lean code it's time to get an adjustable fuel pressure regulator (and guage to tap into the schrader valve). Try adjusting the pressure to 50 PSI to start as oppsed to the stock setiing of 39. Remember to disconnect the vacuum line running to the fuel pressure regulator when checking/adjusting fuel pressure and to put it back on when finished.

Also, what's your base idle set at?