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Surging and hesitating 2.5L

L

Loomster

New CEG'er
Joined
Jan 16, 2005
Messages
8
I have one 1998 Contours, one 1998 Cougar and one 2002 Cougar. My 2002 Duratec 2.5 (Cougar) surges and hesitates when accelerating. I thought by having the dealer change the recalled fuel pump that it would fix the problem. It didn't.
No codes, but very frustrating. From reading many threads I don't see many solutions. Seems like most are trial and error, mostly error. Anybody have any suggestions? Since my other two cars have the exact same motor I can swap parts to try to find the problem, but does anyone have any suggestion as to which part to swap first?
 
How many miles and what transmission? If ATX tranny, you may have a VSS about to go bad or a faulty MLPS sensor.

Did the surging occur after a change of SP or SP wires? Check SP gap and wiring order.

Edit. SPwiring order. Note the 4-6-5 for the coil pack.

Firewall side
4- 6 -5 <--coil pack
3-2-1

1-2-3 <--engine
4-5-6
Radiator side


SP gap should be 0.054 inch.
 
Last edited:
Surging

Surging

Tony:

It has a manual transmission. Only has 50k miles. I replaced all the plugs with OEM ones but that also did not help. Also cleaned the throttle body and MAF sensor. Wiring is fine. The surging only happens when aggressively acceleratingly, about mid rpm's. When accelerating it almost feels like someone shuts on and off the spark for just a fraction of a second which makes the car jerky. If I drive like my wife drives you almost don't notice it.
 
I'm going to keep an eye on this thread, as I have been having similar problems in low rpms and higher gearing.

Since I just recently purchased the car, The plugs and plug wires are going to be changed very soon. But just in case thats not the culprit I'm going to watch this thread closely.
​
 
Loomster said:
.... The surging only happens when aggressively acceleratingly, about mid rpm's. When accelerating it almost feels like someone shuts on and off the spark for just a fraction of a second which makes the car jerky. If I drive like my wife drives you almost don't notice it.
Click to expand...

If by "mid rpms", you mean 3500 rpm and above, I would say you have an IMRC intermittent fault or a clogged exhaust.
 
Clogged exhaust is very seldom intermittent. It is either plugged enough to hurt performance or it isn't.

I would start by running a fuel pressure test and making sure that it isn't a fuel supply problem. Did you change the fuel filter when you changed the pump? If it hasn't been changed for a while, change it for drill.
 
I will check fuel pressure, but since it does not surge at idle or without a load it might be hard to see if the pressure drops. The dealer should have changed the fuel filter when they changed the pump, but I will double check.
 
Check your plug wires for fit, and make sure the power wire for the coil is seated tightly. I had simalar problem, and mine was the plugin to the coil was not all the way seated.
 
I have a surging problem also. 98 SE, mtx, new fuel filter, no real changes when this started occurring. It only happens under light throttle, and only between 2000-3000 rpm. More gas and it goes away, and I have never observed it outside that rev range. I thought maybe a fouled injector, but multiple cleaners later (Seafoam, Redline, Techron) no real improvement. Maybe TPS? It's just enough to be annoying. No other performance impairment has been observed. Idle is silky smooth and idle speed right at 800.
 
i am having this problem low rpm acceleration in 2nd 3rd and 4th gear, i get surging, and under WOT i am losing very noticeable power. im going to test fuel presure this week.
 
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