97 Cavalier 2.2 runs poorly, engine code P0300.
Here's what's been done so far with next to no improvement, each repair done one at a time. Coil packs, plugs/wires, air filter, the following sensors: forward O2, MAP, TPS, crankshaft, replaced the cat. conv. with a straight pipe (inside of cat. was in good condition), compression tested 180 psi in each cyl., has fuel spray in each cyl., has spark to each cyl., maybe unrelated but alternator was NG so a new one was installed, P0300 is too non-specific, I'm getting tired of replacing things based on guessing or process of elimination & feeling it in my wallet. Any help would be greatly appreciated, at least to diagnosis it.
Year : 1997Make : ChevroletModel : cavalierEngine : 2.2
coil packs, plugs, wires, air filter, forward o2 sensor, MAP sensor, TPS, crankshaft sensor, temporarily replaced cat. conv. with straight pipe (inside of cat. was in good condition), got 180 psi compression in each cyl., got fuel spray in each cyl., also new alternator
Welcome. Have you changed the fuel filter or checked the fuel pressure? IT seems you have checked many other things but fuel. A plugged fuel filter is often the most common issue with these.
I did not check the fuel pressure, I'll have to borrow tools to do that (maybe tomorrow) but there was fuel spray in each of the cylinders. Engine idles rough & at very low rpm, like it's going to stall but doesn't, revs up slowly with little power & won't rev past about 2800 rpm, radiator fan runs prematurely with temp in the middle of gauge.
This all sounds like fuel pressure issues. Check the pressure after changing the filter and see.
what about ICM or cam sensor? shouldn't there be other codes besides P0300? Also, I cleared the code & engine light went out, P0300 showed up again but engine light remains off.
If there are 2 cylinders missing all the time then possible the ICM.
I'll change the filter & check pressure tomorrow. Can I reach you again if I still have problems after that?
Simply reply to this post and can continue, even after you accept my answer.
GM Grand Master Technician 2007. 11 years experience.
I'll reply either way to let you know, Thanks
what should the fuel pressure be? is there a range, min-max?
just replaced the fuel filter & no change. I cannot find the valve to connect the pressure gauge, where is it located or is there a different way to connect the gauge?
These need a fuel line adapter that has the fitting in the adapter. It gets inserted into the inlet line of the fuel rail.
fuel pressure at idle is 40, reving the motor it goes up to 45.
OK, and what is the pressure when it is acting up?
it's always acting up. the changes that i've made so far have improved it but it still idles rough & is way down on power. this is a constant condition. it starts up immediately, even when cold & after sitting for several days, when the rpms come down to normal idle after start-up, it's rough & stumbles. after it warms up, the rpms drop very low & it feels like it's going to stall but doesn't.
Ok, for the moment the fuel system sounds ok. A few more things to check. Is there fuel in the rubber vacuum line to the fuel pressure regulator? Is there a vacuum leak, such as the brake booster? Do you have access to a scan tool to view the data from the sensors the PCM is watching?
i checked the inside of the vacuum line going to the fuel pressure regulator & it was clean & dry, did not smell of gas. i checked the intake man. for a vacuum leak but not the booster, will check that now. i do have a scan tool & it only shows one code, P0300, multiple random cylinder misfires. not sure if it makes a different but the only fuel line adapter i could get connected at the filter, in the rear of the car. i thought it needed to be measured after the regulator.
Those are only codes. Does it show the MAP readings, TPS readings? engine temp readings and so on?
Your reading on the fuel is good, it is before the regulator that is needed, which you indicated you did.
here's what my scanner shows
MIL status on DTCFRZF P0300
Misfire monitor ok Fuelsys 1 CL
Fuel Sys Mon ok Fuelsys 2 N/A
Comp. component ok Load_PCT(%) 43.9
Catalyst mon INC ETC (*F) 86
Htd catalyst N/A Shrtft1(%) -33.6
EVAP system mon INC Longft1(%) 2.3
Sec air system N/A MAP (inHg) 16.5
A/C refrig mon N/A RPM (/min) 951
Oxygen sens mon INC VSS (MPH) 0
Oxygen sens htr ok
EGR system ok
OK, the short term fuel trim is concerning, it should be near 0. This means it is seeing too much fuel, but could be due to the misfire.
Using insulated plies, pull the plugs off one at a time, plug wires that is, and see if one or 2 don't spark or cause the engine to run differently.
already checked spark & all 4 have spark at the plugs, runs worse when any 1 of the 4 is disconnected. it's becoming more difficult to start when the engine is hot. brake booster is ok as far as vacuum leak goes.
What temp is the engine seeing from the coolant temp sensor and the intake air temp sensor?
the temp gauge is straight up in the middle, the only thing I see on the scanner for temp is ETC 86* F. I'm thinking maybe water in the fuel, any thoughts on that?
OK, is that with the engine warmed up? If so, then you may have bad gas. A fresh tank is a cheap next step to take.
that is with the engine warmed up. what about the EGR?
OK, this is an issue. Does it run worse as the engine warms up? At running temp, the sensor should see 200 or so. EGR is also a possibility. Try unplugging it.
i took the EGR valve off & checked to see if it was stuck open, it wasn't so i put it back on but didn't try running the engine with it unplugged. what is the ETC temp? as it warms up the idle speed drops & again, low rpms seems like it will stall, besides that it seems like it runs the same. just took the valve cover off to inspect the rockers & pushrods, good oil flow, clean & all working normally.
ECT is engine coolant temp. All the fuel calculations include the temp. If it was reading 86F but the engine is warmed up, then it is reading incorrectly, possibly the sensor, wiring or even a module itself.
tried to siphon the tank but was almost empty, put in 6 gal of 90 octane & ran it for 15-20 min. tried unplugging the EGR, no difference but it threw a code P0405. engine is hot & ETC is reading 86. by module do you mean the ECM, located behind the glovebox?
Yes I am talking about the ECM but it is located in front of the passengers front tire behind the bumper.
just replaced the temp sensor. no noticable change. I cleared the codes after re-connecting the EGR. Again the only code is P0300, haven't driven the car enough for other info to display. I'm sure it must be related some how that when the pedal is held to the floor it won't rev past about 2800 rpm, feels like timing is off. if i feather the throttle it'll rev past 2800 then cut-out, rpms drop & it runs again. Is this a protective thing to prevent over-revving or do you think related to this problem?
There is a rev limiter to prevent over revving the engine when parked. What does the temp sensor show for a temp now?
that menu on the scanner shows "no info stored". I don't think I've run the car long enough for that info to be recorded. I'll check it once more now, then i'm done for today!
Ok, let me know.
still reads "no data stored". This car is not really driveable. no power, pings & bogs down on hills. I've been letting it run parked or driving around the block, 10-15 mph.
I have a thought, you removed the converter, did you remove the rest of the exhaust? I would drop the pipe at the manifold and go for a quick drive.
when i removed the cat, i ran it briefly with only the forward pipe connected to the manifold & it ran the same, i did not drive it that way as it was up on jack stands. I've asked 2 other mechanics about this car. They both agree that I've done just about everything they could think of, one of them questioned the injectors. I know they are all spraying fuel, maybe not optimally but i don't believe it is the cause of this problem. I work for one of our city fire dept. & had our best mechanic look at it, he didn't have much time to really get into it but was stumped. After all this I can only think of 2 possabilities, either the ECM or the timimg chain has jumped. If the chain has jumped, is there a way to check it without having to tear down the front of the motor? and wouldn't the compression be less than 180? Can the ECM be tested?
I have to agree, this is a head scratcher. Injectors could, but so could the PCM and the timing chain. If the chain has jumped, the only way to know for sure is to remove the timing cover and inspect. Testing the PCM is difficult, but given the location, wiring in that area can be bad. Often the PCM is the last guess.
I assume a chevy dealer would be the only way to test the ECM? Should I try swapping in a used ECM from a junkyard? If so, what specific ID's would i look for to get a compatible unit?
If you swap an ECM from a used unit, it will need to be programmed. Testing the ECM is not easy and I suspect even the dealer would be guessing at it.
that's what i thought. i saw a company online that sells them "programmed to your vehicle" for $60. Do you think it's worth a try?
I don't mind doing any repairs the car needs, I'm even willing to replace the whole engine if need be but guessing at the problem through trial & error just doesn't work for me. I need to find the problem then fix it.
$60 for the programming is not bad at all. I think if you are wanting to try a PCM, this is a valid option.
the way it bogs down, has no power & pings, would it be more related to ignition timing rather than valve timing? Ignition timing is computer controlled & timing is read by the crankshaft sensor not the cam sensor, right? I'm thinking there must be a way to narrow this down with all the info I have at this point.
I've ordered the ECM but it won't be in until next week. I'm not sure that's the problem anyway, if it's not then I'll have a spare ECM.
Correct the timing is computer controlled, read first by the ignition module then sent to the ECM. How did all this happen, did it just start out of the blue or was it getting worse?
I bought this car recently for my daughter, figured I could fix a simple problem, the rest of the car is in very nice condition & will make a nice first car for her. This car came from North Dakota, owned by a female who moved out here(east coast) last year. Not sure how the problem started but she said she took it to a mechanic & he replaced the coil packs & forward O2 sensor. It was inspected in Nov. 08 (with emissions) before problems started & not driven since Jan., just started & moved around their yard/driveway.
The ignition module is seperate from the ECM? anyway to test that?
is the ignition module the part that the coils packs attach to?
THe ignition module is mounted under the coil packs.
does this ECM have a "limp" mode? if so, should it show up in the scannner?
Limp mode is usually open loop where it ignores many of the sensors and runs on preset settings.
just finished driving the car 20 miles. no engine light but got 2 codes, P0300 & P0172 "system too rich bank 1". The page in the menu that displays sensor readings still shows "no data stored". Pressing the accelerator any more than 1/2 way makes it just bog down & lose all power. driving it feels like only 15 hp, down to 15-20 mph on small hills. temp gauge stayed right in the middle, tranny shifted appropriately, got it up to 55 mph down hill with wind to my back. I'm really confused!
THe P0172 is system rich. This could be a leaking regulator or leaking injectors.
pulled the plugs to inspect, all 4 the same with some carbon on the ends of the threaded part, the tips & electrodes are clean & again, all 4 equally the same.
Any way to test the regulator or injectors or do i have to replace them & see if it works?
I would pull the fuel rail out and leave all the lines intact when power the fuel pump. See if any leak. HERE is the diagnosis for that code.
I'm off to work, I'll work on it tomorrow night or friday.
Ok. Until then.
i replaced the fuel pressure regulator, no change...no surprise. running the car without the cat, it definitely has a too rich smell to the exhaust, like the old carburated engines that I grew up with before cc. the ecm i ordered just came in but now i'm thinking that your first instinct to look at the fuel system may be it, plus i did get that P0172 code. the only thing left would be the injectors. If I check them as you suggested, it seems to me that whether they leak or not they still could be flowing too much fuel when the engine is running, right? I can get the set of 4, reman. & flow test matched for $140. Should i check them or just replace them anyway? should i try installing the ecm first since i have it now? is there anything special i need to do before or after installing the ecm, pass lock relearn proceedure?
Ok, The injectors may be leaking but they may be over-fueling because of a false reading. Have you tried to run it with the oxygen sensor unplugged?
there's no difference with the O2 sensor connected or not.it does seem to idle a little better when cold (at higher rpm) than when warm/hot but either way, no power.
Since you have the ECM, I would try that. Check the connections at the same time.
just installed the replacement ECM. seems to run a little better cold but still not right & warmed up, the same. i let it run for 15 min then drove it around the block & again the engine light did not come on but scan reads P0300
OK, I have asked another experts opinion to see what we are missing and he suggest checking the Map sensor seal, the injector seals and lastly the head gasket.
I changed the MAP sensor & the new one did not come with a new seal so I had to re-use the seal from the old one. I cleaned & inspected it & it sealed pretty tightly, so I think that's ok. One of my initial thoughts when I bought the car was the head gasket. Both the oil & antifreeze are clean, & as i stated earlier, compression was the same in each cylinder at 180. Also, no sign of oil or antifreeze leaking externally from the head gasket. As far as I can tell, the only things left are the cam sensor & injectors.
OK, I hate to say this, but we are getting beyond what I feel that we can diagnose without live scan tool data, full scan tool data showing what cylinders are misfiring, what the o2 sensor voltages are and much more than that.
this post is turning into a novel. I thought someone would recognize the symptoms & know exactly what it was from experience with these cars. Ever have this much trouble before?
did you receive payment? i clicked accept a long time ago?
I'll try to get a better scan tool than what i have & post results.
Not often is there a post this long, but I have had a couple that were more than 60 replies.
You have paid and thank you.
I brought the car to a friend's repair shop to use the scanner. everyone there seems to have a different opinion as to the problem. here's what i got off a snap-on solus pro scan tool.
O2 varying between 200-800
Short Fuel Trim varying between -14 to -30
In. Pulse 2.5 - 30
RPM varying 450 - 600
Fuel Ind 0%
Fuel Trim Cell 21
Spark Advance 0-20
Increasing the throttle causes the spark to retard.
one suggestion was the valve timing being off & possibly the timing chain being stretched. to check, i pulled off the valve cover again & turn the crank by hand back & forth while checking the valves for movement. there was no slop or play in the chain, the valves moved immediately with turning the crank. is it common to have to replace the timing chain on these motors? it has 171,000 miles on it.
the other guys there seem to describe the exhaust as dropping way off when the motor is revved & thought the muffler may be clogged. I was going to disconnect it (cut it off) to prove them wrong but didn't, yet.
another suggestion was the ICM. I picked up a used ICM with coil packs from a junk yard for $40 & will install that later today, see what happens.
OK, the engine load is what I see that concerns me. 35% at idle? WHat did the pressure reading from the MAP show?
MAP is in the list, 2.26. He was very protective of his scan tool so he read the numbers & I wrote them down.
I'll be heading back down to the shop shortly to get the car back. Are there other parameters you need info on? I just notice the ECT isn't listed but the engine was at normal op. temp. when scan was taken.
Can you ask him what the KPA or PSI is for that voltage? Also unplug the MAP and see what happens.
that voltage of what, MAP? what am I looking for when the MAP is unplugged, any particular changes on the scanner?
I need the actual pressure of the MAP not the voltage, and see if the issue goes away when it is unplugged.
I'll check that now & get back shortly
just got back, the earlier readings were MAP 18 & ETC 195. when I unplugged MAP sensor, the engine initially skipped then ran the same.
unplugging the MAP tripped code 107, here's what the freeze frame shows: Fuel sys1 CL
Fuel sys2 N/A
Load PCT(%) 39.6
ETC (*F) 100
MAP (inHg) 3.0
OK, that vacuum reading is far too low. CHeck that against a regular vacuum gauge and see. Now we are getting somewhere.
which one is too low, the 18 when plugged in or 3 when unplugged? or both?
18 at idle is good, 3 is bad.
ok, we've got some problems here. vacuum gauge is all over the place but in sync with the rough running of the engine, as it sputters the vacuum bounces up & down with it. At low, rough idle, vacuum is bouncing around 10, holding the idle at 1000-1200, bouncing between 13 - 15. As the rpm's go up (no load)with light throttle, the vacuum drops consistantly. I don't have a tach hooked up (is there a place to connect one) so I'm guessing at rpm's. Around 2500-3000 rpm the vacuum is bouncing between 4 - 10, at this point I can here some knocking in the engine, sounds like it's coming from the bell housing. Any change in the rpm & sound goes away. Rod knock or ignition firing too early?
A knocking in the bell housing could be loose torque converter bolts. Also that vacuum at idle should be smooth, not choppy.
vacuum is choppy throughout, but at its worse during idle. At idle, & it's a rough idle, the gauge bounces up & down around 10, +/- 4 rapidly. it's not as rough at 1200 rpm & the vacuum fluctuates around 14, +/- 1.
So what does it all mean & where does this leave me? Drop in another motor?
I would be considering another motor at this point.
A good friend of mine is a motorcycle mechanic. I mentioned the vacuum problem to him & he came over to look at the car. We thought about worn cam lobes & stuck or burnt valves. We repeated the compression test with his gauge & got 210-215-215-220. (previous test was 180 x 4) with such a difference I figured one of our gauges must be off. So i bought a new gauge & repeated the test & got almost the same results as his, 215-220-220-225. Would you agree that with compression that high the top end must be intact & working properly?
Also, I noticed that the #1 & 4 plugs had some carbon build-up on the electrodes where 2 & 3 had none. Since they share a coil pack, could there be a problem in this area?
I don't feel the whole engine has to go, not ready to throw in the towel on it yet.
That is great compression. A problem on 1 and 4 would explain the vacuum readings. Check the coils, wires and so on. If there is 1 wire issue on 1 or 4, it takes out the other cylinder as well. It is the waste spart system.
ok, i got a used ICM with coil packs from a junk yard out of a 2002. I questioned if it is compatible with my 97. According to his computer, it is up to 2003. Does this sound right to you? If it is I'll try swapping that in but won't have time until Sunday.
<p>It does sound correct. Until they changed over to the ecotec engine, they were the same. </p>
I replaced the ICM & coil packs the other day. It runs smoother cold & starts up right away cold but as it warms up it gets rough as before. So, we're still in the same predicament. Could something mechanical cause this, spun bearing, wrist pin ??? I can't even guess at it anymore.
I checked the valve timing just by watching the piston & valves while turn it over by hand. The valves are ahead of the pistons; intake valve begins to open while the piston is still on the up-stroke before TDC & closes before BDC, while the exhaust valve closes before TDC with no overlap. Because of this, I think some exhaust is backing up into the intake just briefly, causing all the symptoms & the vacuum fluctuations. I'll be checking the timing chain, gears & tensioner tomorrow & post my results.
I have to agree, not only because of the fact we have looked at most everything else, but because of the piston to lifters.
That was it! The plastic guide of the tensioner on the right side disintegrated & the inside of the chain wore through the metal part of the tensioner. The plastic guide on the left side, with the spring, also broke but those pieces were intact. At some point a broken piece must have caused the chain to jump as the cam was 3 teeth ahead of the crank.
To remove the timing cover however, 2 studs in the bottom of the cover require dropping the oil pan. To do that I had to temporarily replace the upper motor mount, remove the a/c compressor, lower motor mount bracket, flywheel inspection cover, exhaust pipe at manifold, starter & finally the oil pan, which was loaded with debris (metal & plastic).
I'll update again when it's back together.
Progress!!! This is great. Nothing worse than not knowing.
The car runs great now. Smooth, quiet & plenty of power, cruises at 70 no problem. I guess testing the vacuum should have been done much sooner & fluctuations almost always indicates a valve problem. Finally it's done & I can move on to my next project.
For sure. Whats next?
I've got to fix just a couple of things to get it inspected. I also just finished putting a new 5-speed in my 69 firebird and still have to put in the new shoulder/lap seat belts. But first, I have to finish my younger daughter's playhouse.