I have been running self tests with different results and fixing the codes for weeks now.

I have replaced the MAP, TPS, EVP, ECT, in tank fuel pump, inline fuel pump, filter, put sea foam in the tank, HEET in the tank in case of water from crappy fuel source.

The truck still runs bad. It will run great for a little while then it will die with any throttle imput. It will not go at all. I have to tow it home with my Jeep and them push it into my garage. I am now getting a 67, 84 (the same weather the egr is blocked off or not) and now a 51 (ECT sensor signal is greater than the Self-Test maximum of 4.6 volts.) I replaced that sensor today and I get a new ECT code.

I am lost. I need help

 

We know it's an inline 6 because of the forum your in. I assume your truck is a 92-96 model pickup?

What does a code 67 and a code 84 specifically say what the problem is? You said it pointed to your EGR valve. It might be bad. If pressing the throttle causes the truck to want to die at idle, then it seems to me like the EGR is stuck open and allowing too much exhaust into the motor, killing it. The EGR is only supposed to open and work when your up at cruising speeds, under a load (engine in drive w/ automatic transmissions, in gear with manuals).

What is the new code for the ECT?

Did you check for the obvious stuff? Vacuum lines are all in good condition, no leaks, everything routed correctly, all connections tight, etc.?

It'd probably be a good idea to run the tank empty, then fill it up with fresh gas when you get your problems fixed. That Seafoam can foul your spark plugs, so when it goes empty, get new plugs and plug wires.

Was the truck sitting for a long time before you got to it?

 

Speaking about checking the obvious, when it dies have you checked to see if it's fuel or ignition? Self test and code are great tools but remember they are just tools. Sometimes they tell you what's wrong but, sometimes they just point you in the right direction. Swapping parts just because the computer says it's bad can get expensive and frustrating, as you probably know. Don't forget to do, at least, basic trouble shooting and check things out as best you can before swapping parts.

And as a side note, make sure your battery is good, fully charged and the terminals are clean. A bad or weak battery can cause all sorts of phantom problems with computer controlled EFI systems.

 

Its an 88 with the 5 speed. The 67 is a neutral safety switch and the 84 is an EGR opening not detected. I bloclked the egr and the problem remained. I put a new ignition coil on it yesterday and the problem remained. I don't have a pressure gauge to test fuel

 

If it's saying EGR opening not detected I wouldn't think blocking off the EGR would change it. Have you checked the EGR and vacuum line going to it for leaks? Does the erg move freely or maybe stuck or leaking?

 

The vacuun line plugged into the EGR has no suction to it.

 

The way I understand it that line shouldn't have vacuum when idling. EGR only works when in gear running down the road. But you can check the line and EGR for leaks if you have a vacuum pump/gauge. They're fairly cheap and some parts stores even rent them.

 

I thank you for all your help to this point. The egr is blocked and I am no longer worried about it. But I am switching gears.

I never lost spark completely, but I think my ignition system is the culprit

I was getting really funky readings on the primary side of the ignition coil and am going to pull the distributor in order to inspect the pick up sensor and proper grounding on the TFI IV unit.

 

The first thing I'd do is un-block the EGR, clean it if you can or see if it's bad (and if so, replace it) and hook everything back up to it. Make sure the vacuum lines are routed correctly, and then don't worry about it.

Why was the EGR blocked? The truck being computer controlled, when you start removing smog and emissions equipment, will actually run worse and with less power than it would if it were hooked up.

What an EGR does, it pulls exhaust gases from the exhaust manifold and routes them into the intake below the throttlebody/carburetor, then it flows into the cylinder with the fresh air and gas mixture. This exhaust gas in the cylinder allows the motor to run cooler, allows the Nitrous Oxide emissions to be burnt off, increases gas mileage by making the motor "act smaller than it really is" by taking up displacement in the cylinder, and allows you to run less total timing. When you block the EGR, the computer tries to compensate by using the O2 sensor to tell it whether the fuel mixture needs to be leaned out or rich-ened up. Also, when the EGR is blocked, most motors with distributors need to have their distributor advance re-curved because an EGR doesn't require as much timing advance to run right.

Any performance gains by unhooking the EGR are marginal and minimal at best.

Now if this truck had a Duraspark 2 swap and a butt load of other performance parts added to it, it's a different story. But this is a stock truck (I assume).

So, fix the neutral safety switch, fix the EGR, and there are a few threads on FTE about the ECT and troubleshooting the ECT.

 

Hummmm........

Here's a little something to read about the computers in our trucks.

A9x ECM's (and same years ECM's) Failures Due to Age

I did this repair to my truck and it cured some weird missing issues.

Good luck,

Bob

 

Now that is an interesting read and may answer quite a few questions on running problems.

 

Well I pulled the EEC and the caps were leaking. I replaced all 3 per the website provided a a few posts up and the truck fired right up with no missing or throttle lag....

Until the truck got warm and the problem started again. My next move is on the distributor with the ignition module

 

I'd say there's a good chance the distributor and ignition are o.k. based upon your quote (see the bold).
Once your truck warms up, it goes into a (can't remember if it's closed or open) loop where it adjusts and compensates for the sensor inputs recieved by the EEC.

Have you erased any stored codes and then rechecked for any "new codes" now that you've repaired the EEC ?

I'm thinking you have something going on with an emissions component.
I don't know squat about the 88' series---mines a 94'.

Perhaps a bad o2 sensor ???

Good luck in your quest and let us know what you find.

Bob

 

And one more thing........

Was this truck in your posession and then it suddenly started running poorly or did you just buy it ???

The reason I ask is, a while back someone on this forum asking for help didn't disclose that they recently purchased their truck and it never ran correctly and they were trying to troubleshoot why it wasn't running correctly.

Turns out they had the wrong EEC in their truck.
Apparently, the PO just put what ever EEC he could find in it and then called it good.

So, if the above applies, you may want to pull the EEC out again and talk to a knowlegable person at a dealership parts department to see if you do indeed have the correct EEC for your truck.

The correct one WILL AND DOES make a difference.

Just a thought.......

Bob

 

I have had the truck for years and it just started running poorly. I have taken all emissions devices off to put the truck into limp mode and it runs the same. I did this to isolate the problem and it made no difference. I will erase the codes and run another code check in the morning