Overheating after a bunch of engine upgrades

[SteveR]

In the summer I run a different t-stat. Stock 195 for the winter and a 165 or 170 (don't remember) in the summer. I don't change it till it starts to get real hot though. I haven't had any problems with it running too cool. Went to NAPA and they had 3 temps to choose from.

 

[themud]

Ok so I talked to hesco today and they recommend going the adj regulator route instead of the adj map and larger injectors because, and this is a good reason with 39psi to work with no matter how to fool the computer you still only have the volume of 39psi at WOT....With more pressure you have more available across the board including idle and partial idle, so after changing my tps I seemed to cut down on my long start up time but its still not perfect....

So heres my next question to all the engine gurus is it better to run lean or rich??? with adj regulator I pick up 5psi over current stock setting or should I just leave it and do the Dinos MAT move and call it good at that I know itll run hotter running lean but how much more gas will I waste runnning rich and will that even effect my milage either way????

BTW xjvenom do you have headers, highflow cat, or catback exhaust if not you probably dont need to do any of this yet as your taking in air faster but its not going out faster....

 

[Dr. Dyno]

Unfortunately the OBD II system doesn't like my MAP adjuster modification so if your engine is running too lean and you have this system, my suggested route would be to combine Ford 24lb injectors with an adjustable fuel pressure regulator (AFPR). The stock 49psi FPR is in the fuel tank so you'll need to bypass that one and custom fit your AFPR.

 

[Gojeep]

I run the 99-01 blue tip injectors in my 95 that came with my 00 intake manifold. I dont seem to have any problem running them as the economy is even a little better than before. What I would like to know though is that as these are rated at 22.5lb/hr at 49 psi instead of the stock ones 21.0lb/hr at 39 psi, could they be flowing less than before as I still have the stock 39 psi regulator in the injection rail. Do I have to go to the expense of AFPR or is there a 49 psi one that will fit in it's place? Anything else I should do?

 

[RichP]

What do your spark plugs say ???

 

[XJVenom]

BTW xjvenom do you have headers, highflow cat, or catback exhaust if not you probably dont need to do any of this yet as your taking in air faster but its not going out faster....

Yes, I've got all the exhaust mods. My plugs are much whiter than before (in fact, they were already running a little hot before these major upgrades. I think my injectors have seen better days anyway. They've got over 160k on them.)

 

[XJVenom]

Unfortunately the OBD II system doesn't like my MAP adjuster modification so if your engine is running too lean and you have this system, my suggested route would be to combine Ford 24lb injectors with an adjustable fuel pressure regulator (AFPR). The stock 49psi FPR is in the fuel tank so you'll need to bypass that one and custom fit your AFPR.

I've got the OBDI system (It's a 91) so will the MAP adjuster still work well if I get 24lb injectors? I just ordered some new style Ford 24lb injectors. Supposed to provide better fuel atomization compared to the old style.

Also, I've got the same question as GoJeep. Are there higher rated FPRs available besides the OEM 39PSI that I can use instead of shelling out $200+ for an adjustable? Or are the 24lb Ford injectors I'm getting rated at 24lb even while running with a 39PSI FPR?

 

[themud]

[ What I would like to know though is that as these are rated at 22.5lb/hr at 49 psi instead of the stock ones 21.0lb/hr at 39 psi, could they be flowing less than before as I still have the stock 39 psi regulator in the injection rail. Do I have to go to the expense of AFPR or is there a 49 psi one that will fit in it's place? Anything else I should do?[/QUOTE]


I havent worked out the math yet dont have a cal in front of me that will let me do that but I think theyre actually flowing less than you stock ones.....As far as the AFPR is concerned the only one Ive found in my research was the one hesco offers and its preset to 44psi as benny from hesco told me all jeeps from the factory run lean(could be why we all overheat???) then add performance mods and your way upside down on the fuel curve....It is adj though just requires a gentle touch and some patience I was told have to see soon but I am going to go with the preset and see how it works out if its running rich I can always adj the map then BECAUSE at least I know have the extra pressure and volume to do that with....As for your last question the FPRs in the 96 and up are in the tank and part of the pump assy which is why its cheaper to get the AFPR than a new dealer pump assy(and belive me when I say that autozone wont cut it for pump assy great warranty but itll suck when you replace the damn thing for the third time :banghead: )...gotta wait till I get the funds before I send out for my magic part hopefully in a week or two...
themud

 

[Big Bear]

If you want to further your efforts you might think about hood vents. This would let the additional heat from the new header escape and probably drop your temp 5 to 10 degrees. I am going to wrap my header one day here soon in addition to the hood vents I already have. But these guys are right 210 is normal operating temp.
assgas:

 

[Ed A. Stevens]

Ok so I talked to hesco today and they recommend going the adj regulator route instead of the adj map and larger injectors because, and this is a good reason with 39psi to work with no matter how to fool the computer you still only have the volume of 39psi at WOT....With more pressure you have more available across the board including idle and partial idle, so after changing my tps I seemed to cut down on my long start up time but its still not perfect....

Somehow Hesco's thinking is strange (maybe this needs review)?


91' injectors ~21#/hr @ 39 psi

vs. the typical FMC 24#/hr @ 39 psi

Which of the two will flow more at WOT and 39 psi? (duh, the FMC 24 #/hr).

The 24 #/hr injector will flow up to 14% more fuel at WOT.


Dino's method:

So it may be rich at WOT (because the O2 sensor does not trim the A/F at WOT) but the firmware curves can be trimmed with the MAP (rather than reading 2" WG at WOT the MAP signals it thinks it's at 3.5" WG, and it runs a leaner A/F mixture path in the fixed algorythms).

Open loop conditions except for WOT may still read a little rich but the injector pulse rate will be adjusted slower by the adjusted MAP input to equalize the effor (both at WOT, and off-idle to WOT).

The mixture can be adjusted to run 0-14% richer than stock.


Hesco's method:

Now what if the regulator adjusts 39 psi to 44 psi.

What does a 21 #/hr injector flow at 44 psi?

New Flow = 21 * sqrt(44/39) = 21 # 1.062 = 22.3 3/hr.

Maybe the 91 injectors are ~22 #/hr (CRS?), they will still flow only 23.36 #/hr (the additional 6.2% increase in flow for the 5 psi increase in pressure).

The higher pressure will work everywhere in the computer fuel maps, closed loop (where the O2 sensor will trim the A/F mixture), and open loop (where you will rely on the MAT/MAP and rpm to locate the pulse rate for the injectors).

The result is the mixture can be adjusted for a 0-6% richer delivery of fuel at all times (and a possible increase in atomization, due to the pressure increase, but manufacturers also warn of flow problems at increased pressures).


The choice is yours ...

 

[robs]

If you want to further your efforts you might think about hood vents. This would let the additional heat from the new header escape and probably drop your temp 5 to 10 degrees. I am going to wrap my header one day here soon in addition to the hood vents I already have. But these guys are right 210 is normal operating temp.
assgas:

Didn't help me at all... I even scored a motorcycle radiator fan to help suck out the heat... and it DOES blow out major CFM of hot air...

I'm stock. XJ was extremely well taken care of... flushed every 30k...

Overheat? yah.. in the summer... one blast up any hill will immedately peg it to 230-235F... Both on the trail on on the interstate... just idling in traffic on a warm day will get 225F...

New t-stat, new fan clutch, largest tranny cooler I could find (plate and coil type), previous GDS radiator, now 3 row CSF, water wetter... etc..

Will go with Hesco high flow waterpump and t-stat housing next.

 

[Dr. Dyno]

I run the 99-01 blue tip injectors in my 95 that came with my 00 intake manifold. I dont seem to have any problem running them as the economy is even a little better than before. What I would like to know though is that as these are rated at 22.5lb/hr at 49 psi instead of the stock ones 21.0lb/hr at 39 psi, could they be flowing less than before as I still have the stock 39 psi regulator in the injection rail. Do I have to go to the expense of AFPR or is there a 49 psi one that will fit in it's place? Anything else I should do?

The injectors that flow 22.5lb/hr @ 49psi will flow 20.1lb/hr @ 39psi, so that's slightly less than the stock '91-'95 injectors. Since your engine has a few mods Marcus, I'd be surprised if it's not running lean. To correct that you have two options:

1. Install the Hesco AFPR and bump up the fuel pressure.
2. Swap in a set of Ford 24lb injectors and fine tune the A/F mixture with a homebrew MAP adjuster.

Option 1 may be your best bet.
If you swap in Ford 24lb injectors without doing the MAP adjuster mod, your PCM will trim down the fuelling under closed loop conditions where it reads the O2 sensor voltage, but it'll run rich at WOT or in open loop where the O2 sensor signal is ignored.
If you then add the MAP adjuster and lower the MAP voltage below 5.0v, that'll trim down the fuelling under all conditions. The A/F ratio under open loop can be brought back to stoichiometric (or only slightly rich) while the PCM will use the O2 sensor signal to correct the A/F ratio under closed loop, so it's all good.

 

[Gojeep]

The injectors that flow 22.5lb/hr @ 49psi will flow 20.1lb/hr @ 39psi, so that's slightly less than the stock '91-'95 injectors. Since your engine has a few mods Marcus, I'd be surprised if it's not running lean. To correct that you have two options:

1. Install the Hesco AFPR and bump up the fuel pressure.
2. Swap in a set of Ford 24lb injectors and fine tune the A/F mixture with a homebrew MAP adjuster.

Option 1 may be your best bet.
If you swap in Ford 24lb injectors without doing the MAP adjuster mod, your PCM will trim down the fuelling under closed loop conditions where it reads the O2 sensor voltage, but it'll run rich at WOT or in open loop where the O2 sensor signal is ignored.
If you then add the MAP adjuster and lower the MAP voltage below 5.0v, that'll trim down the fuelling under all conditions. The A/F ratio under open loop can be brought back to stoichiometric (or only slightly rich) while the PCM will use the O2 sensor signal to correct the A/F ratio under closed loop, so it's all good.

Thankyou so much for working that out for me. I have to decide which way I will go about it now with another option of having my old injectors cleaned and refit them. I was thinking later this year of adding a piggy back computer made by Unichip which change the values going into the stock ECU leaving it completely un touched. The stock computer then makes adjustments on what it thinks is happening to the engine according tothe altered values! You can also just un-plug this extra computer at any time and take it back out and plug the harness directly back into the stock ECU. What is good is that it no time do you have to touch the stock ECU. They are made in South Africa and have spoken to them about the Jeep and they had already made one for the OBDII system and were working on one for the OBDI which they wanted me to test until they found out I was not one of their distributors and dont have my own dyno!
This wont help with the low fuel pressure though. I better not leave it too long like this as if it is running lean I could burn some valves if it was bad enough.

 

[rsalemi]

Re: Adjustable FPR

You can make your 39# regulator adjustable with a 1/8" allen set screw and a 1"roll pin.
tap the inside of the vacumn port, then drop in a roll pin and screw the allen setscrew in to adjust the pressure (carefully or you will rupture the diaphram). Grind a flat on the setscrew so the vacumn will still work (legnthwise).
I picked up 14 rear wheel HP by going from 39 to 48 lbs on a stock 4.0 -

 

[Gojeep]

Re: Adjustable FPR

You can make your 39# regulator adjustable with a 1/8" allen set screw and a 1"roll pin.
tap the inside of the vacumn port, then drop in a roll pin and screw the allen setscrew in to adjust the pressure (carefully or you will rupture the diaphram). Grind a flat on the setscrew so the vacumn will still work (legnthwise).
I picked up 14 rear wheel HP by going from 39 to 48 lbs on a stock 4.0 -

This is great information. Do you have any pictures or any other information that would help me to do this? Also how do you read what pressure you have and when you have the right amount for your engine setup. I take the pressure is via the valve on the fuel rail but does it require a special tool or can a tyre guage be used? Do you need to have it on a dyno to set it up right or at least a exhaust gas analyser or can you get away with just looking at plug color?
Sorry for all the questions but have not played with EFI much at all!