My EFI issues

[rockslut]

Ok guys im going to try to figure this efi stuff out. First this is what i have,

'92 mustang engine in a '68 Bronco, auto C4, dana 20, 9'' and 44, 37'' tires
I have had it for about a year now. Engine was installed by prev owner. I did the EGR delete and installed the little plug in the wiring. New O2 sensors, set the tps ,new temp sensor Cleaned the MAF, AIC. used the propane method looking for vac leaks, fuel filters are new. im going to pick up a fuel press gauge on the way home tomorrow. I did find a problem with my in tank fuel pump, the little piece of rubber fuel line that connects the pump to the hardline coming out of the tank was not even all the way on the pump. It was pumping fuel at the line instead of through the line. That fix gave me what feels like 50hp. But didn't fix the idle..

The problems i am having is that at first start up it seems to idle correctly starts off at about 1200rpm then slowly drops down to about 750 after about 30 sec time. Over all runs real strong with no hesitations. After it reaches operating temp 190-195 is were the idle starts giving me prob. I can feel at a stop that it takes more pedal to keep her stopped. At that point if i shift to neutral or park the idle shoots up to 1500-1700 rpm. If i turn it off and restart the idle will hold at 800 for about 5 sec then go right back to 1700. One more thing about how it runs, It runs good but real fat rich. It has always ran rich since i first got it.

So i pulled the neg on the battery for the day to clear anything on there. When i got home tonight i ran it about 10 miles. up and down hills slow driving FAST driving. Kind of put it through its paces. parked it and pulled the codes

first these are the codes engine off key on

82 - Secondary Air Bypass Circuit Failure (O)
85 - CANP Circuit Failure (O)
81 - Secondary Air Diverter Circuit Failure (O)

and engine running codes

41 - System Indicates Lean -passenger side(R), No o2 Sensor Switching Detected. always lean -passenger side(CM)
91 - o2 Sensor Circuit Indicates Lean -driver side(R), No o2 Sensor Switching Detected. always lean -driver side(CM), Shift Solenoid 1 Circuit Failure (O)
33 - EGR Valve Opening Not Detected (CM,R)

I do have a harbor freight elec circuit reader thingy
So i can check stuff but u may have to walk me through that. Like i have said before im much better at racing my big brown truck around delivering boxes, than i am playing with little colored wires. Any help would be much appreciated. Mike

[Rockbronco67]

Re: My EFI issues

Have you looked at your MAP sensor? Not an expert but something to look at.

The MAP (Manifold Absolute Pressure) sensor is part of the fuel management system. It reacts to changes in engine manifold pressure. The PCM (Powertrain Control Module) monitors the MAP sensor continually to properly run the engine. Changes in engine load require changes in the amount of fuel injected, and timing of the ignition system, etc.

Poor running engine Engine runs rich

[rockslut]

Re: My EFI issues

Thanks Rockbronco67, Ill look into it. Ill have to do some reading on how to check it

[pippinmader]

Re: My EFI issues

A couple of things:
- A MAF based system does not have a MAP sensor, it has a BAP sensor (barometric absolute pressure) and it does not have a substantial effect on the system. In fact a well setup system can run fairly well at moderate elevation with it unplugged entirely.

What wiring harness are you running? Home made? Does it still have the "salt and pepper" connectors?

It sounds to me like you have at least two problems combining, 1. excess air and 2. exhaust leak or bad grounds. (It is worth noting that a leak in the EGR system could cause BOTH of the symptoms you are describing because it connects the intake and exhaust)

First off your high idle when warm is because you are getting too much air into the engine when it is hot. All the EFI does it match the fuel to the air, I SLIGHT increase in idle could be from the EFI running rich, but we are talking 50 rpms or something, not double the idle RPMs. The air could be from misadjusted throttle body or, the IAB is confused, or you have a huge vacuum leak. I would look for a vacuum leak first, check the simple things first, is your EGR delete really plugged well, did you check the holes in the back of the heads?
Have you tried manually lowering the idle when it is hot, you can do that by disconnecting the IAB and turning the idle screw on the side of the throttle body. Based on your description it sounds this option probably won't work, which points back to a vacuum leak

- If your system is really running rich but your ECU thinks it is lean you have one of two problems:

1. an electrical problem, the O2 sensor signal is 0-1 volt, so it is VERY sensitive to bad grounds or any other bad connection. Do you have your HEGO ground wire connected to the back of the block like the stock mustang used? Are you sure all your grounds are good? Have you checked and cleaned all your connectors? Again, what harness are you running? If you are running a stock mustang harness and don't have a fair amount of experience with EFI I would suggest an aftermarket harness.

2. I cylinder miss or exhaust leak will cause the engine to think it is running lean (lots of O2 in the exhaust) which will make the computer try to rich up the whole bank, it is a negative feedback loop. Basically it will confuse the hell out of the computer.

The computer can only compensate about +/-12.5% from stock tune, so if you have a large vacuum leak (or header leak) the system reaches its limit before you get the correct a/f ratio.

Good luck!

[Spaceburger]

Re: My EFI issues

Pippinmader has some good suggestions. Check your HEGO connection and especially O2 sensor ground. If the computer can't see O2 feedback, it will run rich.
Check those codes after you've made a few runs, not just one.
Put the EGR back into the circuit. It doesn't affect performance because once you WOT (wide open throttle) the computer shuts it off.
Codes 81 & 82 are caused by the smog pump TAB and TAD valves being left off the build or smog pump disconnected. Again smog pump doesn't affect performance because computer shuts them down when you go WOT.
Code 85 is probably because the CANP sol valve was left off or not connected to the fuel vapor line. Again not a bad thing to keep connected.

[rockslut]

Re: My EFI issues

Thanks again guys i have dedicated Sunday to work on this.
I think pre owner used a mustang harness. I will start cutting zip ties and try to chase this stuff down, check for exhausts leaks ect..

[rockslut]

Re: My EFI issues

Any suggestions on a new aftermarket wiring harness. I have done some searching but haven't found a lot. The electrical in this bronco is very cluttered and chopped up. I figure i could tackle the 5.0 harness first, then next year try to we wire the rest of the bronco.

[California Monkey]

Re: My EFI issues

Summit brand that tony used would be my first choice. I went with the ron francis and I like it but it more expensive and does the same thing.

[Spaceburger]

Re: My EFI issues

I've used the CENTECH Wiring harnesses on two Broncos and I like thier design, price, and simplicity to install. Painless is 50% more expensive, the connectors are not as modern in my opinion, and harder to install.

[rockslut]

Re: My EFI issues

thanks guys..

[CityHick]

Re: My EFI issues

If there are problems with your EFI-specific harness I would take a look at this site: http://www.mass-air.com/Products.htm

They offer a pretty reasonably priced alternative to the $500 aftermarket harnesses. They also have most if not all of the connectors and parts that you would need to rehab an old OEM harness if you go that route.

I am happy with the EFI harness that I got from Summit - its their house brand, everything is new and it fits an EB engine bay just fine, with tons of slack in most of the connections. I have been meaning to cut slack out of a few spots in mine but hate to cut into a "sealed" harness too much.

For the body harness, Centech is the closest thing to a drop in replacement harness with a little expansion (extra circuits) built in. Painless IMHO has a nicer fuse block (basically an OEM GM style fuse block) whereas the Centech block is pretty much fuse holders soldered onto a circuit board with a nice looking housing. Either work just fine.

I used the EZ-wiring 21 circuit (el cheapo) harness off of Ebay. My complaint is that the fuse block is very small and uses compact blade fuses vs. the standard size like what Centech and Painless use. All of the wires are marked along their entire length but the fuse block is not marked (the lid for it is, but is not keyed so it can be installed correctly or 180-out, so troubleshooting is a pain in the arse. It comes with no connectors so that is all on you. Decent end result with it but lots more work.

[California Monkey]

Re: My EFI issues

ez wiring harness has the option for the larger size fuses an fuse block which is what I did. Only thing I'd do differently would be to get a less "deluxe" version as I have about 20 wires I don't use from my EZ wiring harness

[rockslut]

Re: My EFI issues

So I found a vac leek around the egr delete plate. Fixed that. Also found that there was engine paint between the block and the main grounds. Fixed that. I reset the computer and let it idle for about 20 min. There was no serging idle so far. I plan to drive it to work on Friday. So I have my fingers crossed. Still seemed a bit rich. We will what codes it through. Thanks again for everyone's help. I feel I'm making progress.

[1968u15]

Re: My EFI issues

There may be other issues to consider. When you mentioned codes the one that struck me as odd was the shift solenoid code. Do you know which ecu you're using? With your set up (c-4) I would recommend one from a standard trans mass air flow mustang.(that's what I used until I swapped from a c-4 to a 4r70w, a maf ecu from a non-electronic auto trans will also work) It sounds like you have one from an electronic auto trans vehicle, an aod-e or 4r70w. Both of which require a lot of wires to operate the transmission. Most of the other issues you have seem not too difficult to deal with.(just time consuming) When I was a technician at a Ford dealer(70's-90's) the procedure was to fix the key on engine off codes first, then the key on engine running codes then the continuous(intermittent)codes last. If your system is heavily modified you may want to consider a piggy back chip as well. I am using a tweecer on my 68 Bronco and like it because of it's adjustability for a hands on owner like myself. There are also pre-burned chips available also but they cost more and there is a charge for reflashing should you change your set up. Just my opinion, I hope I didn't muddy the waters. Nothing beats EFI when it's working right.