Ok on my truck I’ve removed the catalytic converter long ago and just plugged the EGR pickup tube that goes to the converter. Inside the engine compartment the air check valve is missing (broke off) but that doesn’t really matter since I plugged the pickup tube right? Well it still is pumping air and some smog crap through that somehow but I don’t know how since it’s not got an open end down at the exhaust and it’s not hooked up to anything. Well anyway that makes a clacking noise (the air coming out of that pipe at the check valve) so if I attempt to plug up the connector for the air check valve I won’t be hurting anything but the EGR system right?

Ok also, I accidentally broke those stupid little brittle colored vacuum lines that go from the vacuum tree on the intake manifold to a black box by the battery. What do all these little hoses do? I looked them up in the vacuum diagrams in my Chilton’s book but it doesn’t make much sense to me. I work on small engines not big ones so all this EFI, EGR, etc. crap is just not making any sense to me at all… so I don’t know what I’m doing!

Now, my truck seems to run just fine after all of the above is disconnected/broken whatever. It runs really good actually. It did have some sort of problem where it idled at 2,000 rpm most of the time but I added a helper spring to the throttle body and that settled that. I don’t understand all this stuff and I don’t feel that I have to, but if I can rig something to work (like the spring on the throttle body) and it fixes my problem I really don’t care if it screws up something, who cares it wasn’t working right anyway! LOL. So if all that crap is disconnected or broken, why is it really there? I know the EGR stuff is for emissions but on the vacuum lines I don’t get it.

If anyone has a quick and easy to understand explanation for that stuff I’d appreciate it. Otherwise I’ll keep going like I am since it works fine LOL. Ignorance is bliss!!!! They were right! LOL.
Thanks,
Eric

 

Oh, also I would like it to idle alittle higher. It idles at 700 rpm and i'd like 1,000. it will take off at idle in 1st gear as it is, but if you give it any gas it jerks violently which i'm sure wreaks havic on the U-Joints & gears. So i always give it alittle throttle to take off but i can't really get the throttle at just the right amount, it always goes alittle over 1,000 rpm. Just looking for a smooth take-off and acceleration. Seems no way to adjust it according to the Chiltons. It does have a screw on the throttle body but this doesn't seem to do what i need. I've tried bending the tab that rests against that screw but can't get it just like i want either

Why the hell do we have these stupid EFI's? What the hell was wrong with carburetors? so now no-one can work on their own cars anymore or what? I like EFI as long as you don't have to work on it but hell i can tune a carburetor up down and sideways, this thing is like the non-adjustable carbs on some of the cheaper lawn mowers, except a thousand times more complicated! how stupid! sorry for venting!

 

I recommend that you get a book on fuel injection and read up on it. The EFI system in your 1990 is very simple when you compare it to the OBD-II systems that are in production today. Carburetors were inefficient and emissions controls were extremely complicated. That and most people (you not included) have no idea what is going on under the hood, and wouldn't know EFI or a carburetor from a hole in the ground. Troubleshooting an EFI motor can be harder if there is an electrical problem, but if all wiring is good, it will point you in the direction of the problem without a whole lot of work from the user. EFI's are able to compensate for different air pressures (altitudes), air temperatures, etc, and maximize performance in all instances with no tuning from the user. While you may be able to tune your carburetor for these various conditions, 99% of the people who own vehicles can't. The computer is pretty picky as to the inputs that it sees. Idle speed should stay at 700, go any more and the computer doesn't know that it is idling and will not perform correctly. Work on your clutch actuation, and I'm sure you can smooth things out. Pull the codes from the computer as well, there may be some problem lurking around that is causing the symptoms you describe. The computer does all the complicated stuff, the wiring to the sensors and actuators is quite simple when you break it down. Don't knock EFI just because you are unfamiliar with it. I'm not trying to insult you by any means, but rather just trying to shed some light on EFI for you, because it's not as bad as you think. If it were that bad, automakers would still be using carburetors...

 

Ok thanks. Yeah sorry for venting. I don't have a problem with EFI on the whole and the rest of my family likes it, I just prefer to be able to tinker and adjust things myself. I prefer to make the decisions about how the machine acts. As for the idle, I've heard it should be around 1,000 anyway. I've lubricated it all up as well as possible, but it's still alittle jerky from idle. Maybe a new throttle cable would help? I am smooth with it, but in the future other people may drive it some and I do not want them to rip out my U-joints taking off from idle. Plus it would be more convenient for me as well. Example, if i'm idling through a parking lot and need to apply alittle gas to prevent it from stalling, I have to feather the clutch while giving it alittle gas so it doesn't jerk the whole truck. 700 rpm isn't necessarily a bad place to idle and it does idle smooth, but it just jerks so if it was at 1,000 it would probably not jerk. I'm sure I can fiddle with it some more and get it to idle where I want, i just was venting that these don't let you adjust them much (with tools not computer crap). I am pretty sure we've unplugged the computer and reset it before.

Thanks for the help. I know you weren't being rude or insulting

Oh BTW, the wiring on this truck is a mess too Also the clutch interlock safety switch (that requires pedal be depressed to start truck and i was told it tells the computer when the clutch is pushed in so it idles) the switch had been pulled and a jumper wire installed in the plug. I found the switch hiding behind the sound insulation, but it doesn't function right. I think it just needs taken apart and cleaned real well. It's so simple i don't see how it could be broke. Probably just corroded badly but you can't take it apart. Cheapest I could find was $45 (Some $75 at Ford dealer) for that stupid little switch! Forget that. I'm not made of money. When this breaks I wish I had a Chevy they are easier to work on and parts are cheaper. I just want to go through and rip out all the crap that is disconnected or not being used, or not necessary (emissions stuff) and things that have been bypassed. I know carbs have their downfalls and mainly for people that don't know anything about cars. I would really like an EFI that is adjustable similar to a carb. Well, put adjustment controls inside the cab

 

You can adjust the same things on EFI that you can on a carburetor, with a computer, but it's gonna cost $Texas (from SNL ). Good luck getting all this figured out. Is it possible that the throttle is catching somewhere, so that when you push it, it's not smooth, but it jumps to more throttle than you want? My truck will do that too if I'm not super smooth with throttle application from idle, especially in first gear.

 

well anyway i'll have to eat my words. I went out and fiddled with it and was able to get it to idle about 1,000 rpm. Doesn't idle as smooth but it won't matter unless I left it running while parked. It kinda surges periodically, just a small bit. Probably needs the computer reset. So anyway I tried it in my driveway and now it takes off like I want.
Thanks,
Eric

 

I wont quote all the points in the posts, but I hope this clears things up.....

vacuum thingys and EFI:

on a carb, the amount of fuel is metered due to well know principles discovered by a Mr Bernoulli. A volume of air at some speed creates a partial vacuum with draws fuel out of a capillary. A crude but effective carb. With the use of metering pins, the amount can be tailored vs expected RPM.

however carbs have drawbacks:

1) changes in operating efficiency (volumetric efficiency) of the motor require a re-jet

2) less/more dense air requires a rejet. This density is altered by temp and or humidity. Less dense air at high speed creates the same vacuum as dense air at low speed - so this shows why an intake change, on a warm day, in denver, screws things up.

EFI however tries to deliver exactly the amount of fuel needed, and to do such, it needs to know how much air was injected. Air temp charge sensors, MAP sensors, BARO sensors and even MAFs all help the computer determine exactly how much air was injested - taking into account density (which is affected by temp, humidity, altitude etc) and then delivering lean fuel (coast down), stoich fuel (steady state) or rich fuel (WOT accelerating).

A vacuum leak, mucks with the air measurement taken. missing vacuum tees degrade the performance of the various subsystems on the motor.

In the dark ages - say 1975-1985, a lot of that crap robbed cars of everyting - all in the name of emissions. with the precision of the EFI however, the power has come back in gobs and if you run one in a closed garage, you will die from lack of oxygen long before the CO gets you. This is progress.

 

Hey Franken,

Fixing the vacuum lines is actually quite simple. Take a piece of that hard, brittle line down to the auto parts store and see which size rubber vacuum line the hard line will fig snugly inside. Then buy that size and take it home, cut out all the brittle pieces of the old line and slide the new tubing over the ends of the hard line. This gets rid of your vacuum leaks for almost nothing!