View Full Version : help afte 6000rpm

AAM Cobra 98
09-01-2005, 08:04 PM
hi guys ... i just installed all the goodies in my sig ... my problem is that after 6000rpm the rpm is real slow as the car is choking ... i feel this really good in 3rd gear, in second it is not as bad ... i just changed my plugs and fuel filter ...

a freind told me that it might be my timing is off ...

appreciate your help ...

AAM Cobra 98
09-01-2005, 09:35 PM
any input is welcome ... the rpm from 6000 to 7000 is very slow ....

09-02-2005, 06:25 AM
I believe Ford used two timming ranges for the Cobra. Not sure if this is true for the 98's or not. Perhaps a dyno run may identify if the timming is retarded or too advanced in the upper RPM range. It may also be a miss-fire at the upper end (spark blow out and not burning the fuel) which may be related to spark gap or spark timming. Just a thought. It could also be the Air/fuel mixture.

AAM Cobra 98
09-02-2005, 12:09 PM
thanks for your reply ... as you said am going to change the plugs, what gap should i use with NGK TR55 .... my current plugs are platinum gapped at .35 i got them from the ford dealer i dont remeber the part number but i think it was AGSF32F ....

and about the dyno my problem is we don't have any around here ... is there any other way to check my timing ....

thanks again ...

09-02-2005, 09:34 PM
my current plugs are platinum gapped at .35 That's your problem right there. Stock gap is .054 unless you are running Nitrous, Turbo or Supercharger.

I've had best results with Autolite 764 (copper plugs).

09-03-2005, 01:21 AM
Copper Autolites :thumbsup: Very good call!

Save the rediculous amount-of money from those NGK's and get an extra tank of gas.

AAM Cobra 98
09-03-2005, 07:09 AM
thanks alot for your input ... Autolite is not avalible in this part of the world ... we have NGK, bosh and Denso ... i have bought TR6 plugs and going to test the car today hopefully, if i can get out of office early today to change them ...

thanks again for your inputs ... i will keep you posted on the progress hopefully it is the plugs ...

09-03-2005, 09:49 AM
The best plug I ever had in the 01 Cobra were the Denso Irridiums gaped at 0.035. The Irridiums do not require a large gap and will not foul at the 0.035. As for platinum plugs they get gapped the same as the copper plugs. 0.050 should be fine up to 0.054. I had tried the autolights copper 764's they were good plugs too. I had pinging issues and found the denso's were the only plugs that reduced the pinging to a minimum. The factory plug pinged like hell. The autolights were not that bad but I may have gotten the incorrect heat range and the acceleration seems a bit sluggish. At the time I was looking for plugs, nobody carried them for my year except for the Bosch Platinum +4's which is one plug that should not be used (I tried them and only found that after 50 miles I needed to get them out ASAP due to fouling) I was disappointed since I have used them before in other vehicles and had good results. The denso's are very expensive but I had good results with them. Just my opinion.

If you want the Copper autolights, there is always a means to get them, buy them on the internet if they are unavailable in your area.

AAM Cobra 98
09-04-2005, 03:36 AM
if i order them from the US and pay shipping ... it will be cheaper for me to get the NGK TR6 from here .... i live in Bahrain in the persian Gulf (near Dubai) ..

09-04-2005, 09:29 AM
The NGK's should be fine. I would avoid the double platinums though (they have a platinum plated disk on the ground prong). How much more expensive are the TR6IX irridiums? They are not cheap in the US but if you can get them at a reasonable price (below $11.99) that may be a good thing. The benefit of the irridiums over the copper or platinum plugs (as with the case with the denso's having a smaller electrode surface area, not sure if the NGK's are similar) is that you will get a slight spark advance due to the lower voltage needed to breech the gap and the added benefit of the reduction in plasma blow out that is more common with the stock plug. I am not sure what you would experience with the 98 but I did notice the difference with my 01. I am waiting for new denso's for my 04 which will be arriving shortly. I hope to have the same noticable difference but will shortly find out when the get to my door.

AAM Cobra 98
09-06-2005, 03:20 PM
atlast i changed the plugs and tested the car it feels much better ... i am shifting to 4th gear in .3 mile (the odometer reads 0030) i have the original 3.27 and the t-45 in .... is that ok with all the stuff installed in my sig ...

09-07-2005, 11:02 PM
I would say upgrade the 3.27's to 3.73's or better. I've heard of people saying that having a set of 4.30's in the car is like have the nitrous on all the time. It just rips you out of the hole. Top end and highway driving will suck though. I do a lot of highway driving and currently running 3.73's. I have to say that I'm pleased with how the car feels and not annoyed by the engine rpm. At 60mph the car's RPM is sitting around 2 grand.

09-18-2005, 07:29 PM
I have 4.10's in my '99 and it is great! I spent money on Bassani Cat Back exhaust, cold air, dyno tune, and I got more bang for my buck when I switched to the higher gears. I still get 22mpg on the hwy at 70 i'm buzzing 2600 rpm...takes a while to get used to but after you do, you don't notice it! :thumbsup: