Hello all, new member.

Here's my story(need help):

I took my car to a shop to get a tune up for my E-Test(Ontario, Canada). They did an oil change and said my plugs were fine. So I went to get E-Tested. FAIL.

I took it back and showed them the print out. They then replaced the O2 sensor; PCV valve; cleaned the EGR valve(really plugged); replaced some vacuum lines; the fuel filter; some gaskets; the idle; and the fuel line. Re-Tested. Failed retest.

The thing is, my computer wasn't working(engine light came on while idling, getting the car to a nice warm temperature). So I suggested that they put another in(used). They did and scanned with a Snap-On scanner(the code reader doesn't work, it just says "no data"). It read "Loop - Open", "Rich", and the mixture wasn't switching between from 100 and 900. It was steady at 900/1000.

So the guy was messing around with the O2 wiring and connector. It was switching from not working to working. So he spliced the wire(no connector) and wired the two together directly. He said it was fine(the mixture was bouncing between 100 and 900; and the "Loop" was switching between open and closed) and I left. I changed the spark plugs anyway).

So today I took a spin on the highway came home to get my print out. I left the car running to keep it warm. When I got back into the car, the engine light was on again. So on the way to the E-Test facility I stopped by the shop and asked them to scan with the scanner again. The scanner said the same things that I mentioned earlier. "Loop Open", "Rich", and 900/1000 steady mixture.


Any thought's? Much appreciated.

Added: simply put, how do I fix the O2 sensor from staying closed and stop it from making my fuel mixture "rich"? Wiring problem?

Can you post the rest of the readings from the snap-on scanner. I use 1 all the time and am good at reading it.
With the replaced ecm and it read no data I bet that the replacement ecm is junk or the wrong 1 .
With the check engine light on the system will stay in open loop and will run rich all the time = very bad gas milage + fouled spark plugs =a good way to burn out the cat.
You said the ecm was not working because the check engine light was on well that is what it is suppose to do when it detects a problem.

Here's the thing. The guy that was working on my car also has the same Z24. He took his computer out and put it on mine, as well as his O2 sensor. The same things happened with his stuff on my car.

As far as the scanner goes, he just had that page displayed on it. After he wired the two wires together it seemed to work fine. Also, before this computer was put in, the old one wouldn't work at all(wouldn't read codes or the Snap On scanner). Now that the replacement is in, it works fine(except the code reader...unless no codes were present at that time). He switched the chips from the old one to the new one. It also has the same serial numbers, and make. The spark plugs were fine, they checked them, and then after I replaced them anyway, a friend who works at a dealership looked at the ones I took out. He said they were fine.

I was searching online and came across a few things. Could an injector be leaking? The Mixture Control Solenoid?

I'll post the retest readings pretty soon.

I must say though. I don't smell gas, and my car is running a lot better(it was running really good, but a slight difference can be felt).

E-Test #2 results:

40km/h: HC ppm Limit - 76, Reading - 167
40km/h: CO% Limit - .42, Reading - .46
40km/h: NO ppm Limit - 0870, Reading - 142

Curb Idle: HC ppm Linit - 200, Reading - 447
Curb Idle: CO% Limit - 1, Reading - .80


I've been told that because the NO ppm is good, that it isn't the Cat Converter.

The Hydrocarbons are pretty high, and it's because it's running rich.


I also just finished getting the codes(trusty paper clip). It was 45: Rich Exhaust. Here's what the problems could be: check evaporitive charcoal canister and its components for presence of fuel; fuel contaminated oil; Sticking EGR, O2; leaking fuel injector; fuel pressure regulator. But I was also wondering about the Mixture Control Solenoid.

Does the test reading and code give any hints? Remember the O2 sensor is new, the EGR has been checked and cleaned, vacuum leaks were fixed, spark plugs are new...basically everything in my first post. It runs great, but running rich.

Thanks again people.

HC=Unburnt fuel
What year is it. What engine is it and is it carb or TBI??
Your problem is not a echaust (cat)problem.
Have you rechecked the spark plugs sence the ecm change?? They might be fouled out.
Does the check engine light still come on??
Do you know what the block learn reading is and the intergrator readings.
You might have a leaking injector
HC 447 At idle is way to rich. Are the o2 switching between 0 and 1000 . The block learn reading is very important and so is the intergrator readings this tells us if the computer is seeing a rich or lean condiction and trying to fix it. Are they at 128 above or below that number?
Have them also check the coolant temp sensor(not the 1 for the gauge but the ecm reading) and see if its reading a cold engine if it does that will enrich the system because the ecm thinks the car is cold like a first time start up in the morning.
If the o2 are not switching what are the readings above 500 or below 500

It's and 89 Z24 2.8L. Fuel injected.

The spark plugs were fine so they didn't change them. Then after the ECM was changed I changed them anyway(it was only $15 to buy six, so I figured what the hell).

The engine light only comes on when the car is warmed up. I'll put it into park, then once it's nice and warm, the fan comes on and the light comes on. It doesn't come on while driving. If I shut the car off and re-start it, the light goes away until it is parked and starts to idle.

I was thinking about the problem being a leaking injector. It might be.

The O2 sensor, it stay's at a steady 900 or 1000. They tried another sensor and it still happened. Then the guy took his out of his car(same make/year) and it still happened. This is when he wired the O2 wires directly together, that seemed to fix it...he said it was good to go.

The block learn reading and the intergrator readings haven't been checked yet(what are they exactly?).

I mentioned earlier about the code. The only one that shows up is 45...and 12 of coarse.

These are some of the repairs that it might be, for code 45(from a quick search online):
-fuel pressure to high
-rich injector
-leaking injector
-HEI shielding(open ignition ground)
-canister purge
-MAP sensor
-leaking fuel pressure regulator
-throttle position sensor
-EGR

Thanks again Fireplug. Like I said it runs fine, it doesn't stall or have any trouble accelerating. Like you mentioned, I'm thinking leaking injector .

The o2 is doing what it was built to do. Just because it sets a code does not mean that the sensor is bad. All the code is telling you is that it has detected a problem . Now that problem might be a bad sensor or that it sees something not right.
That is why all the other readings are so important.
Dam put that o-2 wireing back the way it is supposed to be DAM why would anyone do that!!
The block learn and intergrater are the long term and short term fuel programs. What that means is if it is seeing a rich mixture(like what you have) the computer will try to lean out the system and the base 128 reading will change up or down.
Code 12 better be there that means the ecm is able to give you the codes of any problems.
I would do this next
Let the engine idle for about 30 min. do not rev it then shut it down and pull the plugs out 1 at a time and see if any smell like gas real bad or are black in color.
With the plugs out let the engine cool for about 30 min and then have some one crank it over with the plugs out while you stand off to the side and look for a large amounts of fuel getting blown out of a cylinder

I'll try. Thanks again.

Keep idea's coming. I'm taking it to a snother shop...one that I used to go to. My parents have known them along time and they know what they're doing(one of the better places in the area). I went by there the other day to show them what's been done and explained some of the stuff that the other place did. They kind of looked at each other with a look on their faces like "these dumbasses should have fixed it by now".

How is the temperature sensor for the computer.

there should be two, one for the dash and one for the computer.

The one for the computer might not be sensing properly and won't let it go into closed loop.

Would that also cause the computer to heat up? Because the old computer that was in it, the original one that wasn't working, felt very warm.

I'll definitely keep that in mind.

Hey.

I had the same problem with my z24 when e-tested it. running too rich. It's the MAP sensor. Get another one and try that. It's probably what is wrong. If not then I'm not sure. But I'd have to say it sounds like the map sensor.

With out having any data to look at and I hate to JUST THROW parts at it but the next cheapest thing would be go get a map sensor and try it.
Just about any sensor going bad will cause a rich mixture that is why having the data is so important

Well, I took it to the place that I used to go to and they're a repair facility. They went over a bunch of things and said that the only thing they can think of, is to replace the computer with a new one($440 canadian).

I already had the other guy's put a used one in and it seemed to be working. Except you can't get readings with the code readers. The place also said that a car they had before, that they were selling(same make and year) also had the same problem and that they fixed it by putting in a new computer.

I just came back from the dealership too. The guy I know there hooked up a new MAP sensor and the same things occured. So it's not the MAP sensor. He looked at the EGR and said it might be failing, even though the first garage I went to said they cleaned it because it was pretty plugged.

So, since the code readers and what-not aren't getting readings, could it be a wiring problem? The paperclip method does read code 12. Also, code 45 was the only engine light code that came up, but now codes 44 and 45 come up. How could a Lean and Rich code come up?

When the car is revved up to about 2000/2500RPM, it starts to run a little rough. My friend at the dealership said this is when it reads rich. As soon as you rev faster(or slower) there is no problem.

Finally, all I have to do now is take it for the e-test one last time and get the conditional pass($17.50). My concern is that the car runs great. No stalling or trouble starting, no jerking either. It just runs rich.

Does anyone know if it could be a certain wire that is shorting out? I just don't want to pay for hours upon hours of hourly labor for them to search for a wiring problem.

Fuel pressure regulator.

Something is just not right about your statement that they can not read any codes or data but the computer is working ok. If you used the paper clip and got the codes then some of the wireing must be ok.
scan tool that reads all data. Is it at a GM dealer then they should have a Tech 1 scan tool.
Have you bud pull up the ecm wireing specs and then post them here so we can help to find the problem
1989 2.8 does it have a cold start injector?? Cant remember when they stoped that. Now this was a while ago and it was in a w-body that failed e-test but the cold start injector was bad and it caused a rich mixture all the time.

It is a GM dealership. He tried a couple of scanners. He enters all the basic stuff, then it says to look at the engine light to see if it flashes the 12 code. The fan kicks in and the code flashes. He punched a few more buttons and that's when it read "no data".

I'm going to have them check the Pressure Regulator, and the Cold Start Injector(since you mentioned it). I looked up the cold start injector on the autozone site and it's listed for my car.

Another thing. I did a quick search here at the forum for ECM. I was reading most of them and came across some posts that said the ECM for this car is well known for having problems.


Is the fuel pressure regulator hard to install? I looked at it(next to the injectors, on the right side...right?) and it looks relatively easy to change.

I haven't had anything done yet(pressure regulator, etc...), I was wondering if anyone could answer me why codes 44 and 45 are the only ones flashing. It just seems weird to me.

Fairly simple really, the fuel pressure regulator is not regulating the fuel properly and is letting too much or not enough fuel into the injection system.

So simply put, once a new fuel pressure regulator is installed, everything should balance out.

As I mentioned before, when I put a new one on, do I have to put anything on the threads so it doesn't leak(thread lock; teflon tape; etc...)? Does it have to be torqued to anything specific? Or just tightened and then turn a fraction more?

I would like to do this soon because I love my car and I don't want anything to worsen in the coming months. The funny thing is that it runs great.

Thanks again you guys. Not to rush you guys but if I could get a quick reply, it would be very much appreciated...I'd like to do this tomorrow or saturday.


Added: From a search online - if I get codes 44 and 45 at the same time, it says that it's a faulty O2 sensor circuit.

I'll do the fuel pressure regulator first, but if it is the circuit, how do I fix that?

A rich running engine will eat o2 sensors.
I still dont like the idea of no data from the ecm. And think that problem should be fixed first. It just might be the main cause of the rich problem and we are chasing a ghost and not the true problem

I know exactly what you're saying. I just want to fix the cheaper things first. Fuel pressure regulator $100 vs ECM $400.

If the fuel pressure regulator is the problem, it's only a hundred dollars. If it still runs rich, I'll take it back and have them put the new ECM in.

Today I was driving around. I got some gas and went to the store. When I came out of the store and started the car, it was idling all over the place. Then it would stall. It restarts fine, I put it into reverse, then it dies. Restarted and backed up, put it in drive, then it was idling rough again. As it revved up, the car jumped forward.

It did that all the way home...at red lights. Didn't happen while driving.

So I took the groceries inside and came back out, on my way to the mechanic. It started right up and nothing happened...no stalling. It ran fan.

So I get to the shop and explain to them what happened. I let the car idle for a bit(still rich by the way). When I put it into drive, then back into park, the idling was all over and then it stalled.

I'm gonna have them do a fuel pressure test and possibly have them change the fuel pressure regulator.

Also, Should I still go ahead and take it to the other shop and have them put in a new ECM? The downside is that it will be about $440.

try one thing first and then more to the other.

Don't start changing 6 things at the same time.

man you are spending a ton of cash on this problem guessing and just throwing parts at it.
If you still are not getting any ecm data you MUST FIX THAT PROBLEM FIRST. you can throw a entire new engine at this problem and still have it because you dont know whats going on with out the engine data if its wiring or bad ecm have a GM Tech who know what he is doing test your car for this problem

Go to a salvage yard I got mine for $25 US and had to change the prom. Not hard to do. Fuel pressure regulator could be bad hard to tell unless a pessure test is done. Could be a bad Injector since 44 is comming up. Injectors should read 11 to 12.5 ohms. Like Fire said dont throw parts at it very costly.

I did get a used computer. The guy also took his out of his car and it was doing the same thing.

Anyways, I got a new EGR at the dealers cost(with a year warranty). I put it on and everything seems normal, the two screws that are holding the tube on were tight as hell).

I did a fuel pressure test and the pressure was fine. The scanner has the numbers going between 100 and 900, instead of it staying at 900 like before. And it switches between open loop and closed loop now.

I mentioned before that when I revved it up to a steady 2000 RPM that it would start to idle rough and somewhat puff. Well, that's not happening anymore either.

I'll keep everyone informed if anything else happens.

Added: Now my horn seems to be messing up. A year or so ago, someone tried stealing my car and ripped open the steering column. The guy I know at the dealer had one so I went to his house and he put it on. Every so often, when I do use it, it will honk once/twice and then there's a buzzing under the steering column. A wire? Could a connection be dirty?