cold start preheat

[jaynes]

I know this subject is already going on in another thread but I was getting lost! I guess I'm not all that bright! My truck this morning at aout 13 degrees preheated for a total of 4 seconds as opposed to the allotted 10 sec. it was supposed to get. It was alittle more difficult to start this morning. I was reading on another thread that the ecm models are different from the 89's to probably 91. When mine was working right, the intake heaters would come on if the temps were below 59 deg. instead of the 89's 15 degrees, so I'm assuming I have the different one. Are there different ones again for the 92-93? If there are can I swap mine out for one of those? I cleaned all my connections and replaced the thermisor twice. I'm just asking if they're different because I was in a buddies 93 and it was about 72 degrees outside and we were leaving his house in his truck after I had gotten there and his WTS light came on for about 3 seconds or so. He said it always came on for a few seconds not matter how hot is was outside, but that did not mean the intake heaters were going. Why's this? It worked just like the later model dodges and fords and such; always comes on regardless of the heat. I just want mine to work right. Could I swap a later model ecm for my old one?



jaynes



PS sorry so long!

 

[DPetrey]

here is what i have noticed if you plug it in your preheaters wont come on and your wts will come on for about 3 sec and go off. But if you dont plug it in and it gets cold out your preheaters will come on and cause disco lights. Up here in alaska it has been around 30 or so for the last 3 months

 

[JLEONARD]

My grid heater (or the light) will NOT come on at all if the engine is above 56 deg F (or maybe 59 I won't argue the exact number).

If I plug in overnight (I use a timer set for about 2 1/2 hours), and outside temp is above about 10 F or so, the engine thinks it's above 56 and the grid won't come on.

If the temp is a little cold (30s) and I'm not plugged in the grid comes on for about 6 seconds or so (just guessing, I never timed them).

If it's colder, they stay on a little longer... . maybe 10 to 12 seconds.

If I use the grid the truck starts on the first to 3rd compression. If I don't bother to wait for the heater cycle (I'm impatient), it starts on the 3rd to 5th compression stroke.

In the cold weather a good battery is critical to starting... the engine needs to spin fast.

Jay

 

[bgilbert]

In the cold weather a good battery is critical to starting... the engine needs to spin fast.

Roger that. What size group and cca battery do you have jaynes? If you have a big battery, and are worried about it starting rough or hard after only 4 seconds of preheat, turn the key back off, turn it over to the preheat position again, it will WTS and grids will kick on again, then try starting it. I never plug in, and I cycle the grids twice when temps get down to 15*f or below. You can cycle them as many times as you want, but if you have a baby optima or such battery, they will suck the juice and as J said, you want the engine to spin as fast as possible.

 

[JLEONARD]

if you have a baby optima or such battery

OOOOOPs... ... Gulp..... I have a single Optima red top..... but it spins her over good.

Jay

 

[cerberusiam]

Jaynes, yours should work the same way as the later trucks. At least the 91 I drove did. The grid heaters should come on and cycle as long as is needed to preheat the air in the intake horn to their preset cutoff, the colder it is the longer the cycle. If they are not cycling long enough I would suspect the intake temp sensor is not working correctly or a connection problem.



On mine, the WTS light will come on for about 3 seconds when the intake temp is above the preset and no grid cycle. I think it is a module initialization procedure that does that.



If mine doesn't start by the third piston up I shut the key off and cycle again and it fires right away. It won't cycle the heaters again until I spin the motor and clear the warm air fron the intake.

 

[jaynes]

Yeah, usually if it hasn't fired off after the 3rd or 4th compression, I stop cranking and recycle the grids. But still I end up having to do this alot (especially on thursday morning when the forecasted low wed. night is 4 degrees and thurs. high is 12! ). So it's going to be a female dog that morning !



But like on your '92 cerberusiam, the light comes on even if there is no cycle, and i would like that cause at least then I would think that they are working! Plus I think thats cool cause then people would ask "Why does your truck do that?" And then I would say "Cause it's a diesel, and it's cooler than ur car! You wish yours had a Wait To Start light, buddy!!" Sorry I got asked that by a friend once when it was really cold and he was just enthralled.



Can you swap out those control modules from a 92-93 into a 91? Cause mine defiantly does not work the same way the later trucks do, and it's starting to irritate me as the weather keeps getting colder and colder and I have NOWHERE to plug my block heater into. Can it be done? I've replaced my intake temp sensor twice in the past two years and checked all my connections.



jaynes

 

[cerberusiam]

Sorry I got asked that by a friend once when it was really cold and he was just enthralled

LOL!!! Bells whistles and flashy things, gotta love em!!!



I get used to to waiting for the light to go out so every vehicle I get into I wait for the check engine light to go out before I start it. My daughter yells at me all the time "It's not your truck Dad, just start it!!". Sheesh, teenagers are soooooo impatient.



I remember the 91 doing the same thing as my current truck. Jleonard says his doesn't. I am still not sure the PCM has anything to do with the cycle times or activation. I guess I need to start unplugging wires and see what happens.



I know there are different PCM's for different years and functions but not sure if you can swap them between trucks and what it would entail to do so. If the PCM does indeed have something to do with cycle times and such maybe you have a PCM that is going bad. They are such a cheap item we oughta just buy a bunch and swap them around. ( ).



Not to demean or anything, but, are you sure you changed the correct temp sensor for the grid heaters and not the one for the KSB?

 

[jaynes]

"LOL!!! Bells whistles and flashy things, gotta love em!!!"



Heck yeah! Seeing the wait light on my truck before I start it reminds me I got something big loud and powerful under my hood. That's one thing I like about the later models is that it comes on for a few seconds even if it's warm. Just the little things that brighten my day. Anyway, here's what my service manual says:



"When intake manifold temperature is below 59 deg the engine control module (ECM) will energize the intake air heaters for 10-20 seconds. If the intake air temperature is above 59 deg, the Wait to Start light will NOT come on and the intake air heaters will not be energized. " Oh, and I especially liked the part right after that that warns not to operate the grids more than once per 15 minutes, cause it can cause "engine damage". hehe



And also the sensor I replaced was the correct one, and apparently it works both the ecm and the ksb, which I did not know. ECM, or PCM? Cause in my manual it calls it an ECM. Same thing?? So it seems that the ECM is different from 91 to 92 (maybe the 91 you are talking about was a 91. 5?). And if the ECM is bad, I will have to replace it. If they're cheap, maybe I can buy two: one 91 one and a 92 one, see if it works. That would be cool if you could put a 92 ecm in a 91. Any other suggestions? Oh, and where would you find an ECM?



Thanks!!

jaynes

 

[cerberusiam]

Cheap is a relative term, the best price I saw on them was $170 to $190. Shucks has them. There is also a place in FL that specializes in rebuilding them. Can't find the link for it right now. Go figure.



Evidently there are some differences between the years. Mine has 2 temp sensors. That might preclude you from using a later model PCM as my KSB circuit is completely seperate from everything else. Might be why you have a different KSB also. Maybe that is just the way the PCM/ECM was programmed, californy truck don'tcha know. Good luck.

 

[TKingsbury]

Sorry I got asked that by a friend once when it was really cold and he was just enthralled

LOL!!! Bells whistles and flashy things, gotta love em!!!



I get used to to waiting for the light to go out so every vehicle I get into I wait for the check engine light to go out before I start it. My daughter yells at me all the time "It's not your truck Dad, just start it!!". Sheesh, teenagers are soooooo impatient.

I do that all the time when I get into the Mustang. I get in, turn the key and put on my seatbelt while the "grids" are on :-laf .

Travis. .

 

[WJune]

what model or application CTD had No pre heat grid ? If not for a blizard today, I was going to look at a 86 Ford cube van that someone stuffed a 5. 9 CTD, Ford auto trans. into. Guy says it has no pre heat grid. Wonder how they (factory) started that type CTD ?

 

[bgilbert]

PCM and ECM in this discussion are two DIFFERENT things. PCM I believe is behind the glovebox and works with the auto-OD up/downshift, alt, something along those lines, help here, I'm not a 91. 5-93 guy. The ECM is on the firewall driverside, engine side. Read in the other post on this topic, and look over the diagrams Paychk posted, they will show you the ECM! I'm sure it should clarify a bunch for you jaynes. 1200cca group 31 battery, good charging system, good starter, fuel treated with anti-gel, bottle of water dispersent added, no air leaks in fuel system, lift pump up to snub, start/run solenoid operational, antifreeze concentration correct, you can get rid of your ksb, grid heaters, AIT sensor, relays, ecm, or just unplug them and you will be FINE, it will start just fine, simple enough? Did I miss anything?

 

[jaynes]

Now I know what the difference is between the PCM and ECM. I didn't know before, thanks Gilbert. And I have all that stuff you mentioned, besides the my starter, which likes to kick half way out of gear in really cold weather and grind on the ring gear, which also doesn't help cold starting problems. That is why I need all the help I can get until I get my starter replaced... . again. Yes, this is the second starter I've had since I've owned the truck, which is five years, and the first replacement was when the origional starter went out. This is just a crappy rebuild. I saw the wiring diagrams, but don't know how to read them really well. I know where the ecm is. I don't know if anyone has noticed yet, but I'm not really that great with electronic stuff, which is why I'm asking all these questions. That post with the diagrams that Paychk posted, while probably really helpful to those educated in the matter, don't help me all that much. I just want to know why the whole preheat system seems to not be working right. Little things like this bug me, maybe i'm OCD on the matter, and it may not be all that big a deal. But it will bug me to no end until I find out why it isn't working right, and then, how to fix it. I'm really sorry if I'm coming off kind of jerk like, defiantly not my intent, and I'm not trying to offend anyone. If I have, I'm greatly sorry. But, once I figure it out, I will be one happy camper! And the help is greatly appreciated, and it's heading me in the right direction, thanks to you all!



jaynes

 

[JLEONARD]

Jleonard says his doesn't.

Verified it again this morning... the light comes on only if the engine thinks its cold enough for the grids to actually come on.

Also verified in the Mitchell book that is proper operation for an early 91.

Jay

 

[cerberusiam]

The acronyms for the modules are just a pain in the rear. Just like the transmissions, 518 618 46RH 47Rh etc, they change depending on the year, the model and who wrote the stupid book and/or parts reference.



The standard meanings now are:



ECM - engine control module



PCM - powertrain control module





ECM on the eary models is an Electronic Control Module or even and ICM, Internal control module. Either way its generally that big hunk of plastic box behind the battery. The ABS controller is the one behind the glove box and all it does, as far as I can determine, is handle the anti-lock brakes. When the OD came out the controls for it were incorporated into the ECM making it essentially a PCM even though some books still refered to it as ECM.



Some of the late 92 and 93 PCM's had a circuit already setup in them for the lockup converter even though it didn't appear till 94. The only way I can keep it straight is if it concerns engine its an ECM, if it concerns transmission its PCM. The couple of times I had to order a part I told the parts man to just show me pictures of the sections and I would point it out. We were never on the same page as far as nomeclature was concerned.



Jaynes, its all good, no worries. Sounds like yours doesn't have one of the cool flashy things though , you have my sympathy.



Happy holidays.

 

[jaynes]

Great! So everything seems to be working correctly, well almost, except for shortened times. I gues I'll just have to go get another thermistor and try that!



"Jaynes, its all good, no worries. Sounds like yours doesn't have one of the cool flashy things though , you have my sympathy. "



But I want a flashy thing! :{ .....



Happy Holidays

 

[Grey Wolf]

wjune,



The engine ('96) that my son and I put in his '90 came from a FedEx truck and they (Freightliner) didn't use the intake heaters. However we did put the '90 heater back on the '96 engine... .....

 

[MMiller]

Ah just pull the inlet heater off, and hook up a ether injection kit with a push button on the dash. :-laf Thats how diesels without inlet heaters, glow plugs, start. Some perkins I have seen had a nozzel in the the intake that squits fuel into the engine to help it light off with the addition of glow plugs.



There have been days here in Iowa that my truck did not spin over fast enough to start. With 15w40 oil and a cold sub zero day the truck won't start without plugging it in. When it does I get worried because the oil pressure gauge takes FOREVER to show any.



I know that mine cycles a long time when it gets below about 20*F. It usually pops right off then. Bill is correct. If you got enough battery, fuel that is still liquid, the engine will start. It will probably be smokey for a while, but it will run. The smell of raw fuel is great!



Michael

 

[jaynes]

"The smell of raw fuel is great!"



Haha, I love the smell of unburnt fuel in the morning!



Yeah, the only problem is that dang starter. Gotta get that replaced. It makes it alot tougher to start since it kicks out of gear when the temps hit single digits. It starts eventually, though.



jaynes