Power problems when accelerating hard

[fordgt-thailand]

Hi Guys
For a while now we have been experiencing accelerating power problems from slight to very bad performance (7pm range from 2,000rpm up to 5500 rpm (slow building and not smooth). We have replaced the obvious things like spark plugs, coils, injectors, fuel pumps, filters of course engine oil. Which each area of the car we replace there is some improvement. But the problem still is present but not as bad as it was first.
The boost gauge is reading correctly and there appears to be no air leaks in the system.
The power problem is at its most noticeable when cruising wanting to speed up dropping a gear or two and pressing the gas pedal down fairly quickly to accelerate.
If you do a standing start to low speed lower gears the performance is bareable. If you operate the gas pedal gradually the performance is smoother but still signs of hesitance.
I'm thinking waste gaste? Anyone experienced similar problems?

 

[GT101]

Have you replaced the fuel pump relays? - a number of people have had issues with these in the past - they are housed in the auxiliary fuse box under the stowage area latch mounting.

Dave

 

[fordgt-thailand]

Hi Dave thanks for your input, no the relays have not been replaced, had no idea they could potentially cause this problem, I will do this asap and update the post if successful or not. any other ideas what it could be if not relays?
regards julian

 

[fordgt-thailand]

I should also point out, I have also replaced the fuel control models located at the front RH side of the car near the filler cap.

 

[fordgt-thailand]

ok, I've pulled the fuel relays (located in auxiliary box near front latch) for pumps 1 and 2 out, bench tested them both, they both work fine, but maybe under load for longer, they might be playing up, so I've swapped them out with the wiper micro relays in the same location to see if that makes a difference. if so, that would be great to finally nail this problem. will update you. off for a drive

 

[nota4re]

You say that you have replaced the filters - so I hope this means that you have replaced the fuel filter? Your car does not have a wastegate (unless it is turbocharged) so assuming you have the OEM supercharger, you DO have a bypass valve. When you say that the boost gauge is reading appropriately, it makes me believe that the bypass valve is also operating correctly. You can temporarily attach a small go-pro camera to record the bypass actuator and see if it is opening during acceleration. (It should NOT be.) As you have already replaced many components, I would replace the MAF sensor as it is relatively inexpensive.

When the car is idling - does it idle REAL smoothly or does it have an occasional "miss"?

If the problem persists, I would recommend that you attach an SCT device to the car and record several parameters while the car exhibits this problem. In looking at the recorded data, I'm pretty sure we can quickly hone in on the problem.

 

[AMB]

Is your GT "STOCK" or "MODIFIED"?

 

[twobjshelbys]

It sounds like a demand driven issue when the car calls for the second pump. I would replace the relays. They are known to arc and build up "weld" spots. Bench testing would show contact but that contact could be intermittent.

 

[nota4re]

It sounds like a demand driven issue when the car calls for the second pump.

Although a possibility, typically the ecu will know when/if the second pump has not rendered itself on-line and would generate an error code. Not always, for sure, but most of the failures that we have seen have been in parrallel with a fuel pump error code.

 

[nota4re]

OK, here's a checklist;

1. Is the car completely stock?
2. If not, what mods and especially, what is the source of any software upgrades in the ECU?
3. Fuel filter replaced?
4. Good battery and good alternator? (i.e., no starting or voltage problems?)
5. What sparkplugs are in the car (Brand/number)? What is the gap set at?
6. Any engine error codes?
7. What air filters are in the car - have you inspected for any potential blockages?
8. Do you have or have acess to an SCT device?

 

[MNJason]

Are you in Thailand? Bangkok?

 

[fordgt-thailand]

Hi Guys, thanks for the useful input so far, great minds/experience combined usually irons out these gremlins! or at least i hope so.

ok the engine is stock apart from upgraded exhaust (has straight through headers linked up to a custom exhaust silencer, offering better breathing this sort of design had no problems in the past no cats fitted, we have covered some 25,000 miles, the past 2,000miles have been the problem.
it also has K&N air filters fitted 3 years ago to stock airbox, they are regularly cleaned and oiled, but stock everything else.
spark plugs are new motorcraft OEM plugs. (i always fit new plugs every year regardless of miles)
fuel filter has been changed along with both fuel pumps, both fuel control modules also changed, injectors, and fuel regulator, all brand new and OEM.
the fuel pump relays have been tested on the bench yesterday but as one poster pointed out, you cant be sure they are ok 100%, I've swapped them over with wiper relays to see if that made a difference, i had a brief test drive yesterday but it was too short, traffic to heavy to really notice, ill run the car again tomorrow to see if there is any difference.
not sure if this is relevant or not, the fuel gauge after the new pumps were fitted has never read full, it only goes to 3/4's full but the tank is full.
the battery is new, connections are all good. fuses all relays have been changed for good connection etc.
lambda sensors have all be replaced as well, we did have one faulty one, which the EML came up as a warning and fault code under diagnostic scan with basic scanner, i am in the process of purchasing more professional diagnostic equipment which might shed some light on the problem.

right now the car has no errors or warning lights whilst been driven or idling the engine is smooth, easy to start, the rev response stationary is fast and smooth, you would have no reason to think there would be any issue with performance under load.

its certainly a strange one. with every thing I've changed so far, temporarily it feels like its fixed, but drive for longer and its a problem again as it gets hotter, speaking of temp the engine temp does get hotter quicker than it used to, as in when it should be around 180 to 190 its 200. which would indicate its working harder i guess. I also have a transmission problem? when the transmission is cool the gears are working fine, only when up to temp and above that it gets harder to change gear especially if you have been stuck in higher gears for a period of time crusing or pushing at higher speeds (im talking 120 to 150mph cruising. but thats another subject.)

look forward to any other input, ill order new relays to see if it makes a difference anyway.

 

[viva gt]

As suggested by nota4re,,,,,"As you have already replaced many components, I would replace the MAF sensor as it is relatively inexpensive"
Oil from K&N filters can cause issues if it gets on MAF. This is an issue with over oiling filters after cleaning.

 

[nota4re]

As suggested by nota4re,,,,,"As you have already replaced many components, I would replace the MAF sensor as it is relatively inexpensive"
Oil from K&N filters can cause issues if it gets on MAF. This is an issue with over oiling filters after cleaning.

Exactly my suggestion. When OP mentioned "regular oiling" of the K&N filters, this could in fact be the culprit. Change out the MAF sensor.

 

[SMOKDU]

OK, here's a checklist;

1. Is the car completely stock?
2. If not, what mods and especially, what is the source of any software upgrades in the ECU?
3. Fuel filter replaced?
4. Good battery and good alternator? (i.e., no starting or voltage problems?)
5. What sparkplugs are in the car (Brand/number)? What is the gap set at?
6. Any engine error codes?
7. What air filters are in the car - have you inspected for any potential blockages?
8. Do you have or have acess to an SCT device?

Ok if the is not stock and has a BAP then it most likely is a fuel rail pressure spike..because the rails are return less. I had to go into the SCT tune and change the a few items to help with rail pressure spiking. The problem I had was noticed more between shifts (AFTER HARD THROTTLE)then in the next gear at lower RPM it felt like a fuel cut-off. We need more info on your setup. Just an Idea. please explain the exact issue. UPDATED after reading more it does not sound like this but maybe other might at one time have this issue so I will leave this up.

ok I saw it is stock Did you buy it used ? maybe they had some mods done and taken off. sounds like a fuel issue. maybe spark. did you check to see if your INTERCOOLER PUMP is working ?

 

[fordgt-thailand]

Hi Guys, thanks for further input into this problem, the air filters have never been over oiled, just a very light spray, then allow to dry off whipping off any excess before fitting back in the car, today I've checked the MAF sensor (as we have done previously), super clean, no dirt or any sign of oil of any kind, but i will order a new one anyway to be on the safe side(process of elimination). as this has not been changed, the car is a one owner car, no ECU upgrades, only exhaust, straight through ford motorsport headers, onto extractors then silencer. all ceramic coated to cut those nasty high engine bay temps down, which has helped a lot.

the car was running great until approx. 2,000 miles ago, when the power problem happened and our transmission shifting problem got worse when hot.(we suspect shifting cables, thanks to Dave from uk for suggesting this) it was an original thought, we have in stock already, but a pig of a job to replace) was going to do when upgrading the SC to a nice polished more powerful one later)

today we are checking the injection module for any signs of water dirt etc on the connectors, and will today test run the car see if any fiddling has made a difference(mainly from swapping the fuel pump relays over from wiper relays). of course if we had access to proper ford diagnostic equipment for this car it would make life a lot easier and perhaps we will invest in this later to continue the cars upkeep maintenance and solving future problems.

I will also check the intercooler pump to ensure its working, but I doubt very much this is the problem, coolant fluids for both engine and intercooler have been recently changed from last full service done by us.

will update you all later today.

 

[SMOKDU]

Make sure the pump goes on after the engine warms up. You will see water moving inside the tank with the cover off. If it is not working it could pull timing because of the air temp and this could explain the engine running hotter. Just a thought. Otherwise it sounds like a ground issue. Good luck.

 

[RALPHIE]

As they rarely will post online for problem solutions here, you might send a message, e-mail or phone call to Rich & Denis

http://www.thegtguy.com/

 

[BlackICE]

If you have a OBDII datalogger that would be a good place to start. Log RPM, fuel pressure, MAF, and load as you run the RPMs up.

 

[STORMCAT]

The fuel pump relays should be replaced. You can test them and they could pull in but pitted contacts can limit the current and cause intermittent current. The are $12. I've had the secondary one give me problems more than once. They are not sealed and I'm thinking the high humidity areas are harder on relays for obvious reasons. I have along post on this somewhere.