2500 RPMS tops

[BIGski]

I have a 99 XLT 4X4 with a 4.6L, I just bought it for $1300 it had overheating problems...I changed out the head gaskets and up..meaning Head job done, new gaskets heads up !

I have a problem with the max RPM's..I took the truck for a test drive and it was shuddering, so I changed the Trans oil( drained Torque Converter too) added some additive and ran better but still had no power. Got back to the house and realized the max RPM's was 2500...

each cylinder has 150psi compression, new plugs..I am 90% sure I put the timing on correct..have not checked the coils(no COP)

Took the air filter out of the equation, so good there.

Any other suggestions?

While idleing, no missing, checked injectors( seem to be working fine).

 

[dougmcp]

150 PSI is OK if it's even.
Does this thing throw any codes?
Sounds like a fuel filter, timing or COP issue.

 

[BIGski]

Yes, the 150psi is even across all cylinders..

No Codes at all..

Thought about fuel filter !!!

I am pretty sure the timing is correct, I lined all of the marks up when I installed the cams..

Don't have COPs have 2 coils, and will check them to see for sure!

Thank you for replying and helping!

 

[BakerEdition]

could have plugged cats...I have seen that happen before....that could have caused the overheating problem as well...to much back pressure....quick check is to drop the bolts out of the y-pipe at the exhaust manifold and take it for another ride...will be loud but you will be able to tell right away...look also at your exhaust manifolds....if they look white that's another sign of heat...

 

[BIGski]

When I took the heads off, the leak was on the drivers side intake gasket. Both heads were resurfaced and are good now, but the shop said they had gotten hot!

I will take the pipes loose at the manifolds and try that...won't be for another day but it is worth a shot.

Thanks for all of the help! I will let everyone know as i check things out!

 

[KWT2000]

stuck egr valve will cause that problem also

 

[BIGski]

changed fuel filter...nasty nasty nasty...

checked both coils, using the manual. Primary check is within tolerance for Ohms...secondary check is over the tolerance for Ohms...

decided to mess around with the vacuum lines...

am able to get full throttle when vehicle first starts up...then idles rough and will not go past 2500-3000 rpms...

tried different things and was giving slow thottle and was able to achieve full throttle some of the time....

Then a coolant line busted...Will work on issue more when I replace the Heater/coolant line that busted..

 

[BIGski]

Ok, new heater hose is on and good...

Back to the original problem...I can get full throttle as long as I do not just mash on the peddle all the way. It will go up if I gradually give it gas. Took truck for a test drive and seemed good at first then started to have no power..

I am getting some new gas to put in the truck tonight and will check to see if that is the problem...

 

[BakerEdition]

I still say you got plugged cats or a bad TPS switch...if you have had the heads off just drop the bolts since they will come off easy and drop the y-pipe down and see if it can breathe....remember Beverly Hills Cop when they stuck a banana in the tail pipe? LOL

 

[dougmcp]

If it's not exhaust, it still sounds like water in the fuel or a bad fuel filter.

 

[BIGski]

I was thinking bad fuel as well, so I just took the truck to the gas station and it drove fine up to around 35 mph. So, I stopped by a local parts store and they ran some codes(no engine light on)...codes P0171, P0113 and P0102.
Was told they are the MAFS, an air sensor and a lean bank !! Purchased some MAFS cleaner and will clean it first thing in the morning..

any other ideas ?

 

[BIGski]

BakerEdition had the problem diagnosed from the get go...I was able to drop the nuts from the exhaust and noticed a big difference as soon as I started the truck up !!!

After I got the code for the MAFS I replaced it anyway...

Tomorrow I go to get the exhaust cut off..well at least the cats !!! Any suggestions ??

 

[BakerEdition]

Hey Big, don't know if you will find someone to cut those cats off..if so...good deal..if not, here is a link to some long tube headers and off road y-pipe that eliminates the cats....if you had the heads off the manifold bolts will come out nice and easy..this would be easy for you to do..and they are also set up for the upstream O-2 sensors...you can leave the back two off.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200669457125#ht_2244wt_698

 

[BIGski]

Thanks Baker, I have a friend that knows everyone !! I am going in the morning to get the cats cut off...will let you know how it goes..

And for that freeze plug that had a wire in it, it ended up being like a block heater and was messed up..I think I fixed it..will see tonight..

 

[BIGski]

Cost $40 a piece per cat, times 4 cats = $160.00 to get my cats cut off. Problem is fixed from the original problem of wont get more than 2500 RPMs. Vehicle drives and accelerates good now.

THank you to all who helped out!!

Now, I have a couple of codes that come up...but I will post this in another thread..