'97 Ranger 2.3l misfiring after rebuild

[hoppy]

took the injectors in yesterday to get them rebuilt. I''l get them back from the shop tomorrow or friday, and I'll let you guys know what's happening.

 

[hoppy]

update.

Last week, I got the injectors back, and 2 of them had poor flow, 2 had fair flow. One of the poor flowing injectors had a drip leak. Before the rebuild, they were mismatched within 22.2% of amount of flow between the 4 of them, and after the rebuild, the flow is good and they are matched within 1.1%.

Put those in, and still had a code for idle air control error, so we replaced the idle air control valve, reset the computer and it seemed to run okay, but still had a misfire.

I had driven it about 100 miles yesterday, and the check engine light had not come on so I got the code reader and it showed no codes, and that it would pass smog. I immediately took it to the smog place, and it passed with flying colors. It's hilarious that the check engine light came right back on 2 minutes after I left the smog place!!!!!! it was a code for the idle air control error again...most likely for high idle as it was idling at 1200rpm, so I backed the idle screw off to 800rpm and reset the computer, and it hasn't come on again....yet.

I have an appointment with the dmv to get my tags today, and we'll be back in business, and no more back-up cars or back-up cars for my back-up car.

It still had a misfire though, and we figured that it is probably one of the coils. My dad's thunderbird's coils are the same part number so we swapped them out last night, and the truck ran really smooth, no misfire.

Hate to jinx it, but I think that it's fixed.

 

[hoppy]

Got my tags today, so it's CA legal to drive, which is good.

Somehow, there's still a misfire, and the check engine light came on giving me a code for cylinder 2 misfire.

It only misfires when it's cold and warming up. We were thinking it could be another sensor, like camshaft position or crankshaft position sensor, but I would assume that if there are problems with them, then I'd be getting another code for those too.

Any ideas?

 

[scotts90ranger]

have you changed plugs and wires? if a sensor was acting up it wouldn't be pointing at one specific cylinder. I would concentrate on the passenger side plugs as they are the primary set

 

[hoppy]

We put new plugs and wires on when we replaced the cylinder head, and that was done 3-4 months before we rebuilt the engine and began this troubleshooting process. So the plugs and wires are about 8-9 months old at the most.

It wouldn't hurt to replace them again because they've been handled a lot more in that amount of time than they normally would be.

As I mentioned in my last post, it misfires when it's cold. It's a really bad misfire, feels like it's just running on 3 cylinders. AND the CEL started blinking about 5 minutes after I started driving, I know that means possibility of severe damage to the cat.

It shouldn't be the coils, because we swapped those off my dad's tbird (same coils, same part number, etc., perfect match) and the tbird didn't have a misfire at all. We swapped the coils to eliminate the possibility of the coils being the problem. The plugs and wires aren't even a year old, so those shouldn't be the problem. We had the injectors rebuilt, so those are spraying nice and clean and shouldn't be the problem. We fixed the connector on the TPS, replaced the idle air control valve AND backed off the idle screw so it now idles at ~800rpm instead of 1200rpm. We checked compression in each cylinder and they all test at 150psi+.
We haven't checked the fuel regulator on the fuel rail, or the fuel filter, or checked the pressure coming out of the fuel pump, or the actual fuel pump itself. Although, the fuel pump has been replaced within the past couple of years, so it's not the original one from '97.
Could it be water in the fuel tank? Rust in the fuel tank? Clogged fuel filter, or malfunctioning fuel pump?

I feel like we have a good idea of what's not causing the problem. We're definitely narrowing it down.

 

[hoppy]

My dad had a good point: the misfire happens when it's cold, but it's gone when it warms up, so whatever is wrong with it, it has to do with temperature, so it wouldn't be a fuel pump, or a cam/crank shaft sensor because those things don't depend on temperature to work properly.

We think it's the bank 1 (upstream) oxy sensor, and people on other forums have said that the common code for that if it's not throwing a code specifically for bank 1, is a cyl 2 misfire code, which is the only code that it's throwing now.

regardless of what we have tried the current issue is a severe misfire only when cold that is TOTALLY GONE, RUNNING LIKE "GREAT" once it is up to temp. so bad wire, bad injector, fuel pressue etc etc, in my opinion, cant reasonably be the prob because of the fact that TEMP is determining something and switching from barely running to running great in a few minutes time. I have heard of an "open loop" issue with an oxy sensor. and we have not put one in yet, but soon.

 

[hellion]

I have the same truck, same problem, and its only gotten worse, a little bit at a time for a while. then daily worse after a few months. NOW it stalls if i get over 3k rpms when its cold, and rpms drop to 4-500 rpms and lope back to normal after warmed.....

Amusingly, I had the same experience with CES and smog as well. so ill pitch in with other things ive tried so maybe between the two of us we can get a damn solution lol.

Egr valve, TPS, IAC, CoilS (Both), Plugs, Wires, Manifold gaskets(Intake upper and lower and Throttle body,) vacuum lines(the hard plastic set of three that travels through everything) PCV, Thermostat, air intake temp sensor, MAF sensor, fuel filter, and finally, the Crankshaft Position sensor... phew....looking back, thats like, nearly 900$ ..... now i REALLY regret not going to a mechanic.... havent tried injectors, but youve already tried that.

 

[hoppy]

youve done it all except the oxy sensor too

 

[hellion]

youve done it all except the oxy sensor too

were talking o2 sensors right? from cat?

 

[hoppy]

yes, one upstream, one downstream of the cat. I dont know if thats out problem, but going to find out.

 

[hoppy]

ALSO, we have a 180 degree thermostat, instead of the oem 195, so that keeps the engine from getting as hot as it needs to in order for it to run properly, and that might keep our upstream o2 sensor from getting hot enough to function correctly or at least until it finally warms up.

We're going to swap the upstream sensor for another one that we have that works, and see if there's a difference. Since thermostats are cheap, we'll probably put a 195 degree one in there.

 

[hellion]

ALSO, we have a 180 degree thermostat, instead of the oem 195, so that keeps the engine from getting as hot as it needs to in order for it to run properly, and that might keep our upstream o2 sensor from getting hot enough to function correctly or at least until it finally warms up.

We're going to swap the upstream sensor for another one that we have that works, and see if there's a difference. Since thermostats are cheap, we'll probably put a 195 degree one in there.

My ONLY problem with that idea, which might be wrong, is if the thermostat wasnt letting it get hot enough, or letting the o2 get hot enough, it would only effect it at running temperature. Im not 100% on this but theoreticaly, wouldnt NEITHER have any effect on things while its still cold? If it runs like dogs*** from the getgo, it has to be something that can effect it while still cold, ie; sensor issue, vacuum leak, a temp problem that goes away due to thermal expansion? Idk , thats my idea, id like to here how yours turns out.

 

[scotts90ranger]

yep, was going to add something similar.

 

[JC 97]

My ONLY problem with that idea, which might be wrong, is if the thermostat wasnt letting it get hot enough, or letting the o2 get hot enough, it would only effect it at running temperature. Im not 100% on this but theoreticaly, wouldnt NEITHER have any effect on things while its still cold? If it runs like dogs*** from the getgo, it has to be something that can effect it while still cold, ie; sensor issue, vacuum leak, a temp problem that goes away due to thermal expansion? Idk , thats my idea, id like to here how yours turns out.

The o2 sensors are not heated by engine coolant.They have a heating element in them.After the exhaust temp hits 600 degrees the o2 goes into closed loop mode.So if the heating element is bad, when cold the o2 could malfunction causing a mis-fire.After it gets hot enough it starts to work properly.

 

[hoppy]

We checked the upstream o2 sensor, and it had continuity when we tested it with a multimeter. Our idea to swap it with another one off my dad's truck (spare) fell flat because although they were the same part number, the connector was different. So, we still have the same upstream sensor installed, and we think that it works fine.

What about the egr valve? We were checking the vacuum coming from the hose that connects to the top of the egr valve, and the suction seems really weak. I know that the egr compensates for a cold engine somehow, so maybe the valve isn't opening when it's supposed to or there is another part where the egr goes into the manifold that is plugged up. The exhaust is always hot, so it should be doing its job when the engine is cold, but it's not and that might be why it misfires until its at running temp.

We also put on the 195 degree thermostat, we thought that the one that was in there was 180, but it was actually 192. So we have a new thermostat that will allow it to get a little warmer.