Hi, I am new to the forums. Have been on the site many times, but finally needed some technical info.

I am currently working on a Ford 2.9L bronco II. The engine runs great when it is cold. But after warmup the idle drops down to about 500 rpm. When I try and push the throttle the engine dies. When I shut the engine off and let it cool for about 5 minutes it runs fine until it warms up again. I am thinking this may be something in the distributor (Ignition module) or the such. Help would be much apprieciated. Thanks

 

First thing to do is pull the codes. The O-2 sensor is ignored at wide open throttle or when the engine is cold (open loop) whats it do when you floor it?

 

When the engine is cold, it revs right up and runs great, then gradually as it gets warmer sometimes is bogs for a second then revs up. When engine is upto operating temperature it will kill the engine if floored.

 

Welcome to FTE!

Bad ECT (engine coolant temperature) sensor maybe?

 

I'm 87 XLT: start with trouble codes from the computer (see www.dalidesign.com/hbook/eectest.html for instructions). Remember that codes point to circuits rather than to individual components. If/when you post the codes here for further help, it helps to not only give the actual code numbers, but also to note which type of code each is (KOEO hard fault, continuous memory code, or KOER).

 

wow, thanks for the great information. I will definately do this and see what I come up with. Had no idea you could retrieve codes this way. Neat. I'm still an FE man, through and through. I like carbs.

 

Hi,

My mothers 86 Bronco 2 had similar symptoms. After too much searching to list, it was finally determined that it was a bearing on the distributor gear that was seizing up. It would run fine when cold, but once it got hot that was it.

Just sounds similar to yours.


Ron

 

HI. New to the forums as well.
We have a 87 2.9 that seems to have similar symtoms...
It runs just fine, as long as it's cold. Seems, as soon as the thermostat
pops open, it runs like crap. One thing I saw someone post caught my
attention - when the throttle is wide open, it also seems to be o.k.

We've already replaced the ignition module, rotor, coolant temp. sensor,
and fuel filter. The check engine light doesn't come on, which is one thing
that is boggling us.

The odd thing, is that it was running just fine, then one afternoon, it just
started doing this...

Going to try a new 02 sensor this week, following the advice of an earlier
post from 87 XLT. I'll post up my results as soon as we get it done.

 

Welcome to FTE!

You should also try and check your fuel pressure when it's cold and then again when warm to see if there is a difference.

 

Your 87 does'nt have a check engine light. Anytime the engine is'nt running right the FIRST thing to do is pull the trouble codes. This is very simple to do & takes about 2 minutes. I have an Actron CP-9015 that cost me about 30 bucks at Pep Boys/is very simple to hook up & use & comes with an XLNT instruction manual. So the first thing to do is pull the trouble codes & post them here. Heres just 2 examples of how simple a code scanner can make your life.
When MY 87 was pinging/stalling off the line I hooked up the code scanner, 2 minutes later it flashed a code 53 "throttle position sensor voltage is to high" A couple more minutes to test the TPS with an ohm meter & sure enough it was shot. Took a couple minutes to replace it & problem solved. When the cruise control quit working I pulled the codes & got a code 29 "vehicle speed sensor- signal voltage is too low". Replaced the VSS & that problem was solved. So take the 2 minutes to pull the codes & post them here.

 

Shows you how much I know about this damn truck, heh. Only had it a few
weeks so far...Thanks for the heads up on the phantom light, 87xlt, hehe.

I guess I will change my plan of attack, to grabbing a CP-9015 today,
and hopefully pulling some codes to make this all a lot simpler.

Thanks for the welcome guys, and the quick response advice!

cheers!

 

one approach would be to clean the egr sensor. i have an 87 ranger with a 2.9 and i had the same problems. cleaned out the egr and replaced the O2 sensor. ran like a champ afterwards. My codes were a 13 and 31. Low rpm selftest fail, and i cant remember what the other ment. LOL