1987 gt 2.8. Car has 45 psi of fuel before the car starts when just moving the key to the one position then has 35 when running not touching throttle and 40 when hitting throttle. If you stay off the throttle it will idle but its very rough and wants to die then finally dies. Just replace coil cap and rotor. This is a rebuilt 2.8 stroked to a 3.1. If I didn't give enough info just say so.
I have the exact same.issue with mine mines a 3.1 with a 2.8 topend. And a 7730 swap The common response I've gotten was my compression is too low....... I can make it come down to idle if I hold the throttle ever so slightly but the second I completly let off the end it stalls. I'm still working on it if you figure something out Please let me know and.I will definitly do the same
Well I put in a Brand new IAC and basically no change. It still wants to die and will hardly idle for longer than 5 seconds. The rpms go down to about 500 then up to about to 2000 then jumps around and will hold at 2000 unless i blip the throttle then rpms fall and dies. When driving the car if I hold the throttle it will go then it will act like you let off the throttle then go again then act like you let off. Kinda like its surging but slowly.
My friends Fiero just did this to him. it would start but if you didn't hold the throttle it would die. I swapped his IAC with my IAC and it ran fine. The IAC was stuck shut. So if i were you i'd check that if you haven't already.
99% sure it's not a vac. leak. I have an acetylene torch and used that to go around the engine it never changed, but never the less it is possible I didn't put it over the leak.
On the Ogres site there is an IAC reset procedure which closes the IAC all the way and when I reset it it will idle at 1000 just fine but once I plug the IAC back in and drive or give it throttle in neutral/park it starts its stutter again.
I have the exact same.issue with mine mines a 3.1 with a 2.8 topend. And a 7730 swap The common response I've gotten was my compression is too low....... I can make it come down to idle if I hold the throttle ever so slightly but the second I completly let off the end it stalls. I'm still working on it if you figure something out Please let me know and.I will definitly do the same
I wonder if adjusting the throttle cable a little might help that?
I would double check that IAC is working and that it has a good seal. Using RTV before reinstalling helped a slightly rough idle condition. 2nd on the EGR, I bypass mine, but they do get a little stuck.
[This message has been edited by plane (edited 04-27-2013).]
Now on cold start it will start up perfectly then as fast as the RPM's go up they fall back down and it doesn't try and stop itself. When warm it is idling at 1500 in neutral and 1200 in drive.
I took the EGR valve off and sprayed cleaner in it but what is the proper way to check and clean the EGR?
I am going to recheck for VAC. leaks and check my TPS. Anything else?
check your timing, if its too advanced it can cause a high idle. Since you just changed out the cap and rotor, the timing might have gotten bumped a lil bit. You might also have more leaks somewhere else as well. Also, since you have been messing with the engine sensors don't forget to reset the ecm so it can learn how they are supposed to be.
Well I took the IAC out again today and cleaned the whole with Blue Showers and rubbing alcohol then used q-tips until they came out with no carbon. It now Idles low but on a cold start it wants to die unless I give it gas and will surge when trying to take off in gear. When warm it will idle and not surge in gear.
When I say cold I mean right when I start it when it is cold it will die right away unless I give it gas. If I rev it up for about 5 ten seconds then it will idle.
Well I took out my distributor and cleaned it up a little now the car won't even start? No matter where I put the timing.
Edit: Installed 180 off. Runs again.
Edit: Car still stumbles after cleaning inside of distributor.
Also the car will not die on any start up but when cold it is a little hard for it to find its idle it seems. When pushing the throttle really fast and letting off to make the RPM's go to about 2500 it revs great but if you rev slowly it will sputter a little then go up in RPM then fall then go up then go down and will hardly hold RPM if its being held in neutral but when at speed 30 and over it will hold a steady speed with no surging.
[This message has been edited by Shonyman32 (edited 05-02-2013).]
How long has your car been acting like that? Did you buy it like that or did it just start happening? Could it possibly be your throttle stop screw closing your throttle to much?
Take out your IAC and put a rag over it so the pintle thing doesn't pop out. With the IAC plugged in but not in the throttle body turn the engine to the ON position without starting the engine. Does your pintle move at all?
Take out your IAC and put a rag over it so the pintle thing doesn't pop out. With the IAC plugged in but not in the throttle body turn the engine to the ON position without starting the engine. Does your pintle move at all?
No, ive taken it out ans started the engine and it doesn't seem to move at all.
The other day I put injector cleaner in the engine and took it for around a 70 mile drive it now idles better and takes off from a stop better. Put premium in and more injector cleaner to see if the problem goes completely away.
Car now is running very bad. Car will not idle and will only stay running if I flutter the throttle otherwise rpms drop and it dies. If you Rev it up then stop the rpms fall but at around 400 rpm on the teach it tries to stay alive for about a half second. If I keep the throttle in the same spot it will die. The throttle must be constantly moving in order to let the car continue to run.
If the injector cleaner improved things and then things got worse, there must be loose junk floating through your fuel system because of the cleaner....I would do it again with something stronger that is available at many repair shops. After I bought my Formula, I did that 3 times before all the junk got out of the system. Change the fuel filter again too.
I have been filling up with only premium and putting injector cleaner in ever fill up. Today I took the car to my old high school shop that has a scan tool. Some readings were: O2- only went from 440 to 460 Stayed in open loop temp was 67C or around 160 tish tpss had good numbers and one number stayed on 128.
I took the car out today and got on it pretty heavily got up to around 75 and its now running decent but won't idle still. I am definitely running rich. Spark plugs are pretty black.
Originally posted by Shonyman32: I have been filling up with only premium and putting injector cleaner in ever fill up. Today I took the car to my old high school shop that has a scan tool. Some readings were: O2- only went from 440 to 460 Stayed in open loop temp was 67C or around 160 tish tpss had good numbers and one number stayed on 128.
I took the car out today and got on it pretty heavily got up to around 75 and its now running decent but won't idle still. I am definitely running rich. Spark plugs are pretty black.
OK, you did not state if you had any codes set when you ran the scan. The biggest clues in what you stated above is that it "stayed in open loop" and the "O2 - only went from 440-460." Let's first look at Open Loop: Any time an engine is operated in open loop, it runs somewhat rich and makes more exhaust emissions, which translates into lost power, poor fuel economy and air pollution. As a side note, "open loop" simply means that the ECM is using a pre-determined set of values to operate the engine functions. "Closed Loop" means that all sensors including the O2, coolant, and MAP are operational, sending condition data that are read by the ECM which directs the proper fuel mixture command to the injectors for maximum operating efficiency. Let's look at your O2 values: When the engine has more fuel than needed, all available oxygen is consumed in the cylinder and gasses leaving through the exhaust contain almost no oxygen. The O2 sensor then sends out a voltage greater than 0.45 volts. If the engine is running lean, all fuel is burned, and the extra oxygen leaves the cylinder and flows into the exhaust. In this case, the sensor voltage goes lower than 0.45 volts. Usually the output range seen is 0.2 to 0.7 volts. (The sensor does not begin to generate its full output until it reaches about 600°. Prior to this time the sensor is not conductive and produces no voltage to the ECM). The mid-point is about 0.45 volts. This is neither rich nor lean. A fully warm O2 sensor will not spend any significant time at 0.45 volts. If the ECM senses a steady 0.45 volts, it knows this is an "illegal" value and then judges that the sensor is not operating. At that point, the ECM directs that the engine stay in open loop. These clues seem to be leading to a faulty O2 sensor. You probably will not be able to check the O2 sensor since it requires a high impedance digital volt meter. Due to the sensor cost, it is simpler to replace it with a new sensor. GM part # for all years, all engines is #25162693; automotive parts stores stock these sensors also. Some other things that can cause rich conditions: Fuel pressure. The system will go rich if the fuel pressure is too high. Leaking injectors, including the cold start injector. Fuel contamination (specifically for contamination with oil). Check the canister purge for fuel. If full, check canister control and hoses. Check the MAP sensor. If the ECM detects a lower than normal vacuum then this will cause the system to go rich. Disconnect the MAP sensor. If the rich condition goes away, then a problem exists with the MAP sensor. Check for leaking fuel pressure regulator by checking the vacuum line to the regulator for fuel. Check TPS. An irregular TPS output will cause the system to go rich due to a false indication of accelerating. Rectify the rich condition, and I think you will be just fine. Start with the O2, your scan showed it as failing.
Robert- First the tps is completely functional and functioning correctly. Verified by my fathers meter and scantool. For the injectors I replace all six on the rail with known good ones cleaned by me, and spray tested with perfect cones and no leaks. Did not replace the cold start injector though. I did unplug it today with no affect though. The fuel regulator has no fuel in the Vac. Line.
Is the map sensor the sensor by the air filter or the the little box sensor withe Vac. Line running to it?
There were no stored codes. This led me to believe that the 02 sensor was still operational?
Is there any other way of telling if the car goes into closed loop other than a scan tool?
Originally posted by Shonyman32: Is there any other way of telling if the car goes into closed loop other than a scan tool?
Using diagnostic mode (with the paper clip across A&B of the ALDL connector) is the best method other than a scan tool. When the SES flashes get very fast it has dropped out of closed loop. If you use the paper clip in the ALDL and start the engine you will see what I mean about how the frequency of the SES flashes drops to about 1HZ( Slower) when the ECM goes into closed loop. Then as you drive the car you will notice the length of the On flash lasts longer than the Off flash when you accelerate indicating a rich condition; and the opposite effect when you get out of the throttle. During steady speed the flashes will be of equal On/Off duration. Should the ECM drop out of closed loop the flash frequency will speed up to about 2HZ (Faster), like when you first started the engine.
BTW, I would not remove the paper clip from the ALDL with the key on...just a precaution against static discharge.
What you may not know is that a rich mixture causes several problems as well. • A rich mixture will send more unburned HC into the catalytic converter to be burned, which overheats and destroys the converter over time. • A rich mixture will foul spark plugs, reducing mileage even more and exaggerating the effect on the converter as more unburned fuel enters it. • A rich mixture causes carbon build-up in the cylinder, reducing the life of the piston rings and possibly causing them to stick. • While a rich mixture does lower combustion temperature, a rich mixture will wash oil from the cylinder walls, reducing lubrication and causing the oil that is washed off to be consumed.
Something to think about... Many O2 sensors that are badly degraded continue to work well enough not to set a fault code-but not well enough to prevent an increase in emissions and fuel consumption. The absence of a fault code or warning lamp, therefore, does not mean the O2 sensor is functioning properly.
Things that could be causing your problem, please don't think I am repeating myself, because I am... Since we know you have a rich mixture: • Bad fuel injectors (spraying a stream instead of a fog) • Bad O2 sensor (reading lean all the time, so ECM richens mixture unnecessarily) • Bad ECM, or running in open loop due to failure of some sensor needed for correct closed loop operation • Insufficient coolant (ECM does not go into closed loop)
I will give more info she I have time but your last sentence says insefficent coolant. Would running straight water have an affect?
Actually, I left out the word temperature. It should read • Insufficient coolant temperature (ECM does not go into closed loop) But, to answer your question, I don't run water for anything other than pressure tests. I would not use regular water for an extended period. It will cause more problems. Antifreeze helps keep corrosion away and does aid in cooling.
I no longer have a cat. No spark plug has fouled "yet". Also it will die at idle but dies less while hot and will and will die faster with fan running.
Just unplugged the map sensor. Idled about the same but held rpm better and revved up smoother in nuetral. Unplugging it did throw a code but I plugged it back in and code went away. Unplugged it and plugged it back in several times to get a good judgement.
Also thanks for all the great info. That really helps.
The reason its straight water is the engine just got a complete overhaul and I was anticipating leaks and I didnt't want to loose or let antifreeze drip everywhere if there were any ( which there was two coolant leaks although fixed now). I supposse putting antifreeze would be a good idea now.
