It was the injectors themselves. I could use a good injector cleaner in the tank and it might help a little, but the relief was temporary.
They were all triggering, electrically receiving signals at any rate.
Yours might be different.
At that time the injectors for the 2.8 were about $60 each.
What codes are you seeing? What does the vacuum gauge do when it is bogging? Sounds to me like it may be a restricted exhaust... HTH, Ben
ok most of the time. But randomly out of
I unbolted the exhaust at the manifold and it still did it, and i am not getting any codes
runs ok most of the time. But randomly out of
where are you located?
do you have a access to a voltmeter or oscilloscope?
as another posted mentioned, even a small light bulb might be helpful to monitor the voltage that the ECM is sending to the injectors...
If you have a small 12volt light bulb connect it in parallel with the injector. The brightness of the lightbulb should be an indication of the amount of fuel the ECM is asking for. When you open the throttle, the light should get brighter..
If I recall correctly, the detail of this is that the voltage is really always 12 volts but the there is a very fast on off pulsing. When more gas is needed the on time is increased. A light bulb will average out the on off pulses so you will see the light get brighter when the on time is increased calling for more gas. An oscilloscope would be the right way to look at this if you can get one.
If the bulb does not get brighter then the ECM is not asking for more fuel. Then that means the ECM is bad or more liekly one of the sensors feeding info to it is not right.
The three main sensor are the TPS throttle position sensor, MAP sensor which measure manifold vacumm and the engine crank sensor which also triggers the spark.
Mark
runs ok most of the time. But randomly out of
Thank you for this information, I have a voltmeter and a test light but no scope. I tried to find out how much voltage was being sent to the injectors, and i found that it was a constant 12v after that i was not sure what to do. I will try what you said, but i think i read somewhere that it is dangerous to connect a test light to the injector connector?
Oh yea, and i am from eugene oregon
Harbor Freight or other places offer "noid" lights that are specifically made for this purpose. They are not expensive (at least I dont consider them expensive)
The waveform is a square wave, approximately, of ca 12 volts. The amount of current drawn on the average is determined by the firing time and a function of the impedance of the injector.
Just because you see a firing pulse at the injector does not mean that the injector is opening properly. But there WILL be a difference current between an injector that is opening versus one that is not.
One more thing, the noid lamp tells you only if the injector is receiving firing pulses. It tells nothing about current, etc., in its common embodiments.
Remember also that those pulses are coming from an ECM or PCM. If you should do something ill advised with a voltmeter or common test light, like shorting it to ground, you might sizzle some expensive electronics.
I see thank you for the advice, i really am doing my best to fix this car. hopefully i will get it done soon
please come back and tell us what you have found...
Mark
Here is where I am at now, The whole time i had been working on the car the fuel pressure gauge has been hooked up. Pressure always looked perfect. During the bog the pressure showed no drops, it actually would increase do to the regulator getting less vacuum as the motor picked up. It always showed the exact specs it should. This is what made me think it was not the pump or fuel lines, so i looked to the sensors and wiring, every thing looked great electrically. I checked the signals from the sensors right at the ecm and all looked good. Then all the sudden the engine started idling bad for the first time and the fuel pressure gauge needle started jumping. This is the only time the car had ran odd other than bogging at acceleration, and also the only time the fuel pressure did any thing odd! After this, i started thinking that i bet that even though the pressure is good
99.9% of the time something is still not right between the tank and the motor. So, I plan to inspect the fuel lines, filter, pump and tank for debris or blockage. If there is none i have a good feeling the pump is going. What do you think? And since this one incident the pressure has been stable and the bogging continues....
I may have missed it, but did you look at the MAF? I saw sort of the same thing on an 80's Buick, though (IIRC) it happened more on hills. (Loading, all the same.)
G
Car has no MAF, but i did check the MAP sensor
I think that to solve this, one way or another, you you are going to have to monitor the pulses from the ECM to the injectors. It can be done safely if you don't short any wires together or to ground.
Is this car multi-port injectors or single injector throttle body?
Mark
Ok, how do i go about checking the injectors exactly? I checked and had 12v, to one wire but i don't understand how to find out how the pulses are changing as you push the gas... It is multi-port injectors, so they are really hard to check under the plenum. The only other way i know to check them is to use a light and that will not show the changes you speak of it will just show that it is firing the injector right?
If you have a laptop, you can get an adapter to connect it to the car's OBD output. The software that comes with the adapter (among other things) lets you run a trace on the various sensor signals, as the computer sees them. So, you could drive through one of the faults, and see if it showed anything interesting. (The trace display would let you examine the dump in a more lesurely setting.)
I bought mine at
George
Will he be able to get at the computer that way when the car is that old (1990)?
The software that comes with the adapter (among other
Look for a new battery on ebay or run the laptop from the car's electricity using an inverter to convert to 110V AC.
I know a divorced woman who owned a 1987 Oldsmobile.She blew the engine in that car. cuhulin
I know a divorced woman who owned a 1987 Oldsmobile. She blew the engine in that car. _____________________________________
Divorce doesn't stop natural human desires.
Rodan.
:
are you still working this problem?
I think the brightness of the light will give you an indication of changes of the pulses...
If you step on the gas I would think the light needs to get brighter..
Also I think at this point you can troubleshoot your problem with one light connected to one injector... we are not checking the injector itself but instead we are checking the signals that the ECM is sending to the injectors... so far we havew no reason to think that the ECM is sending the wrong signal to only one injector, so checking any one should be the same as the others...
Mark
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