• Welcome Visitor! Please take a few seconds and Register for our forum. Even if you don't want to post, you can still 'Like' and react to posts.

Proper operating temp, low power at higher speeds OD


raggadie

New Member
Joined
Mar 11, 2014
Messages
34
Reaction score
0
Points
0
Vehicle Year
1986
Make / Model
Ford
Transmission
Automatic
I have two questions.

First, what is the proper operating temperature for a 2.9 engine, or thermostat rating.

Secondly, I have great power in lower gears, but I do have trouble climbing hills in 3rd and 4th (OD). What issues would cause lack of power? That way I can start to eliminate the last of the problems I have with the truck.

One last question. Is it best to run 87 gas in these engines?

Thanks for the timely responses,
Ross Wood
 


RonD

Official TRS AI
TRS Technical Advisor
Joined
Jun 2, 2012
Messages
25,291
Reaction score
8,294
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
Gasoline engines have best economy, performance and oil lubrication with coolant temp between 195degF and 225degF.
Ford thermostats are between 190-195degF, usually 192degf

Remember t-stats set MINIMUM operating temp, and has nothing to do with maximum temp, i.e. overheating.
If you have a cooling system problem engine will overheat with a 160, 180, or 190degF t-stat, or even no t-stat, lol.
So running "cooler" just costs you money in fuel and increased oil contamination, it is not "better" for the engine.

Lack of power under load could be low compression, on high mile engines the rings are the most common issue for low compression, compression test and leak down test is best way to find that out.
Vacuum gauge($25) can also help ID an engine issue, good read here on testing and results:
http://www.gregsengine.com/using-a-vacuum-gauge.html

Exhaust system that is partially blocked can also cause lack of power at higher RPMs, cat converter or muffler is collapsing inside, exhaust pressure at the valves increases so less air/fuel mix is pulled in.
See vacuum test

EGR system, if so quipped, can put too much exhaust gas into the intake causing lack of power under load, that is when the EGR system is used.

Low fuel pressure/volume can lower power when fuel is at high demand, under load, change fuel filter($10) if you don't know how old it is, check fuel pressure for drop at high RPMs

Yes, if engine is not pinging then 87 octane is fine to use.
2.9l has a 9.0:1 compression ratio, so it was made for lower octane fuel.
When engines are made with compression ratio above 9.5:1 they can start to get "pingy" under load with 87 octane.
Octane is strictly a heat rating, 87 octane will pre-ignite under compression and heat at a lower temp than 89 octane, pre-ignition = pinging/knocking
87 and 93 octane have the same "power" per gallon, so MPG and performance will be the same, IF engine runs well on 87 octane.
Higher performance engines run above 10:1 compression ratios so HAVE TO run higher octane, but the higher octane is not why they are high performance engines, the high compression is.
Some will run a tank of 93 octane now and then because it has additives that clean fuel injectors, I use a can of Seafoam once a year.
 
Last edited:

raggadie

New Member
Joined
Mar 11, 2014
Messages
34
Reaction score
0
Points
0
Vehicle Year
1986
Make / Model
Ford
Transmission
Automatic
The thermostat just seems to be operating funny, even though it is brand new. The temperature seems to differ at times. Some days it is fine, others it rides the N on the norm.

The engine is new, so there should be no problems with the rings. I have also replaced the exhaust. Along with this, I have replaced many other parts too. For the most part, it runs great, just needs that extra power at higher end. Lastly, I removed the EGR system, and updated it with a computer that doesn't have this system.

What I have done is; changed the coil, wires, plugs, cap, button, replaced a good deal of sensors (most), put new filters for fuel and air, cleaned the MAF, and like I said above put a new exhaust on it as well.

The truck is a 86, what else could I be missing?

Also, I will be looking into a fuel pressure tester because the truck is old, and it is something that could be causing the problem. Other than not knowing the pressure, it seems to work fine, but I know that isn't a tell all sign.
 
Last edited:

RonD

Official TRS AI
TRS Technical Advisor
Joined
Jun 2, 2012
Messages
25,291
Reaction score
8,294
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
If you removed the Temp Sender on the intake, it has ONE wire, did you happen to put sealant tape on it's threads when reinstalling it?
This ONE wire sender uses the intake(engine) as the ground in the circuit, so it needs at least the lower threads to be bare for a good ground.
(There is a TWO wire Sensor that looks similar to the one wire sender, it is for the computer, so not used by the temp gauge)

To test if temp gauge and wire are good, turn key on and remove that ONE wire from the temp sender, gauge should go all the way down, now get a short wire and Ground that ONE wire to battery or engine, gauge should go all the way up.
If this happens gauge and wire are OK.
Also there is a Ground strap from drivers side head to the firewall, make sure that got hooked back up and is tight on both ends, this is a main ground for the instrument panel.

Your year used a MAP(manifold pressure) sensor to set baseline air/fuel mix, it is on the firewall passenger side, it has a vacuum line and electrical connector, it is often hidden behind wiring harness.
Remove and check the vacuum line, remove and inspect the electrical connection for corrosion, where it sits can get water intrusion.
MAP sensors rarely fail.

Could be fuel pressure issue, should be between 35-45psi, if you do rent a tester run engine at 2,500rpms for a minute or two and see if pressure starts to drop, on older vehicles the screen(sock) in the fuel tank can get clogged up which lowers the volume of fuel available when demand is high, pressure looks fine at lower RPMs but will steadily drop at sustained higher RPMs.

Make sure to use Motorcraft spark plugs and gap them at .044

Get spark timing light and test timing with spout connector off and on, then rev engine and see if timing is advancing as it should.
Base spark timing(spout connector removed) should be 10deg Before TDC, some thing 12 deg is better.
Good read here on TFI system: http://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml

If your spark isn't advancing as it should power curve drops off at higher RPMs.

If you used headers to get better low-end power that power is taken from the top-end, headers don't "add" power, they move the power band lower or higher, but that doesn't read like your issue.

One thing you might check, is if your year and engine has a Knock Sensor, I am not sure???
A knock sensor will cause retarded spark timing if "it thinks" the engine is pinging/knocking, this will rob power at higher RPMs.
I have read some '86/'87 2.9l engines had these, usually on starter motor side just above oil pan.
read here: http://www.therangerstation.com/forums/showthread.php?t=91259
 
Last edited:

Sponsored Ad


Sponsored Ad

Staff online

Member & Vendor Upgrades

For a small yearly donation, you can support this forum and receive a 'Supporting Member' banner, or become a 'Supporting Vendor' and promote your products here. Click the banner to find out how.

Truck of The Month


Kirby N.
March Truck of The Month

Recently Featured

Want to see your truck here? Share your photos and details in the forum.

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store


Sponsored Ad


Sponsored Ad

Sponsored Ad


Amazon Deals

Top