Thanks Ray. I had read from other places (the link on page 1 of this post I think) that the middle pin was the ground. That might explain why I wasn't getting good voltage while checking the top pin. The bottom pin is definitely the 5 volt pin. I will try the middle pin today when I get home...Still waiting for the stupid TPS adjusting tool to get here so I wont' be able to adjust it, but atleast I'll be able to tell if it's way off or not. As for probing, I've created a connector out of the old TPS plug and some wires that I can use to tap into the wires while it's connected.
Checked the TPS again using the middle pin and a ground. Got about the same (.05 V) on TPS.... also got 2 error codes from my ECM: 21: WOT switch is shorted? (also says in the haynes manual that sometimes 21 can be a problem with TPS, or both WOT and TPS) 44: lean exhaust Any ideas?
Matt, I am not surprised at the reading from the ECM regarding the code 21. It is essentially saying that the readings are close to ground, exactly what it should read under the circumstances. I suspect that the middle wire is either grounded somewhere in the harness, or the ECM itself may be grounding it, due to an internal issue. The only way to isolate the problem is to disconnect the wire from the ECM connector, and try the reading once more. If it still shows that low, I would suspect a grounded harness, or one that has been "repaired" at one time. Let's be sure that, at this point, that we are on the same page. The key is on, the TPS connector is connected to the TPS, and the black lead is on a good ground, regardless of where. To be sure, try going to the battery positive, looking for 12 volts. If the ground is correct, try this: Turn the key off, and disconnect the TPS connector. Using the ohmmeter, connect directly to the TPS, in the carb. Not the wire connector, but the TPS connector. Going from the middle pin to one of the end pins on the TPS, try moving the throttle, noting whether the resistance either rises or falls, gradually. If it does, we are looking for a harness or ECM issue. Next step, again, with the key off, using the ohmmeter again, connect between the ground and the middle pin of the TPS connector, this time on the harness side. Note the reading. Then disconnect the ECM connectors, at the ECM end. I believe that there are two. Disconnect both. Again, on the wire side connect the ohmmeter between ground and the same middle pin. Note the reading. Tell me what they are, and we'll go from there. In an overview, at this point, I suspect a wiring issue, or a defective ECM. We can test, and we need to be sure before we go spending money. If the middle pin on the wire harness end is shorted to ground, there are two possibilities: one is that the wiring is grounded in the harness, and that will need to be repaired before continuing. That will show up when you disconnect the ECM from the harness, inside the car. If, when you disconnect the ECM, the reading does not change, it is likely a wiring issue. If, on the other hand, disconnecting the ECM changes the reading, it is likely an issue of a shorted ECM. We need to test carefully, double checking everything, and THEN draw conclusions. According to my technical literature, the following wire colors are for the 5.0 Y engine: the gray wire has 5 volts supply voltage on it, and it goes to pin 21 of the ECM. The ground is black, and it goes to pin 22 of the ECM. The signal wire, which is dark blue, goes to pin 2 of the ECM. Can you verify these wire colors for me Matt? Looking at your car, at the TPS, those wire colors should be in the connector. One more thing you might check Matt, is whether, when you make a resistance check on the TPS connector on the wiring side, is whether any of the wires appear to be shorted to each other, particularly the blue and black wire. Let me know... Ray
Thanks Ray, I will check that stuff out ASAP. We are in the middle of a snow storm...yay maine. but as soon as I can get out there I will. one questions, where is the ECM located, if you know? EDIT: Nevermind, i looked in my repair book and it says the ECM is behind the glove box.
The ECM is typicaly in one of two spots, either on top of the glove box, where it typically is located in the trucks, or inside the passenger side kick panel. Usually, the kick panel simply removes using one or two screws, or push pins, and the panel comes right out. Though it may also be behind the radio, my diagrams show it behind the pass. kick panel. After Thurs, I will be out of pocket until the following Sat. I will keep in touch until then, but hopefully, I have provided the necessary info for a fix. Please feel free to ask questions, there are no stupid ones. If you want an answer, it is not a stupid question. Ray
Ok, so I got my TPS adjusting tool last night. I checked my little "testing harness" I had made, and found that it had broke and was causing the ground...so I fixed it, hooked up the tester and adjusted the TPS to .48 V at idle. opened the throttle and saw the reading go up to around 4 V, let it go and it returned to .48 V... I was happy until I started the car up and took it out for a drive. For the first minute it ran great. Accelerated good, back to normal. After I stopped at a stop sign, the problems returned. This time, no check engine light came on. But there was still no throttle response. I'd push the throttle...and nothing would happen. The car would just coast along. If I feathered the throttle (pushing it down and letting off of it constantly) it would actually go a little bit faster, but as soon as I gave it a constant throttle...no response. Any ideas?
Sounds like something else going on. Check accelerator pump function and float level. Also check the fuel pump.
will do. The Accelerator pump seems to function properly, is there an official way to test it? I push it down with the car idling and it revs up nice. How would I check the float level? And how can I check the fuel pump without dropping the gas tank? Would like to avoid that if possible.
so I've made some progress... the non-responsiveness has turned into just a shutter/hesitation... My friend (who is a ford mechanic at the dealership) thinks it's related to the transmission now...I've checked the TV cable and it seems good. Here's what's happening: Car idles perfect. Put it in D, there's a slight shutter on take off...give it WOT and it takes quite a while (about a minute) to open up, then when it opens up the 4 barrel kicks in and it drives great. Let off the gas, slows down...Give it gas again, same results. In 1 and 2, WOT works perfect. In 3, sometimes it works perfect, sometimes it doesn't. Also note that the break light is still on. Fluid was wicked low, filled it up and it didn't help at all. Any ideas?
When was the last time the carburetor was rebuilt? Have you checked the timing using the correct procedure? The 307 is a very low performance motor. You should not expect big things from it especially in a big car. Is the transmission downshifting when you floor it?
carb has never been rebuilt as far as I know. I know the 307 is very weak for this car, but this performance is not normal. Timing wasn't changed (as far as I know...how would it have changed?) When I floor it, I'm not sure if the tranny downshifts or not. flooring it results in some shaking and hesitation before it reacts. After it does react, the 4 barrel kicks in and it picks up speed like normal (or close to normal) but when I push the gas again, same shaking and hesitation.
You have to remember there is ethanol in our gasoline. Sooner or later, that will affect the rubber parts and gaskets in the carburetor, especially the accelerator pump. If the accelerator pump is not up to snuff, that would account for all of your symptoms.
Also, you should feel it upshift back to 3rd after you let up on the pedal, if in fact it has dowshifted to second when you floor the gas.
the problem with the brakes... rusted out brake line coming off the master cylinder where it meets the frame...Yeah, good stuff. Hopefully getting that fixed tomorrow. Carb troubles are almost all gone, did a little more work on it today and went cruising. Choke is messed up a bit (have to hold the choke plate in for a few minutes on cold start or it stalls??? Anyone know how to adjust?) Hesitation is almost gone...still there but not nearly as bad as it was. Not sure what's causing it or how to make it go away, really frustrated right now and considering buying a rebuilt q-jet...
I did buy a rebuild kit. My girlfriend's father was going to help me rebuild it, as he knows more about carbs than I do. After looking at the rebuild kit he said it was too complicated for him to rebuild... Anyone know a reputable place to get a carb rebuilt? I'm in southern maine but wouldn't mind sending it out to have it done.
I would have Cliff Ruggles rebuild it, I do not know of many people who are very familiar with those late model q jets.
Matt, First, let me say that the 307 is no pig. When properly tuned, it runs quite well, even for a smog motor. Check this: the timing, as I recall requires a special procedure to "fix" the timing at the base for the adjustment. If the timing is adjusted without using the correct procedure, it will be retarded some 6 -8 deg. As I recall, it requires that the ECM be set in the code read position for the timing check. That means that, when checking the codes, the same connections are used for the timing checks, only it is put in this condition AFTER the engine is running. Do you have a dwell meter? Dis you check for the condition I spoke of with the cannister purging? There is a valve, close to the carb, with some four vacuum lines running to it. Disconnect and plug the ones going to the carb and re-drive. We'll start there. DO NOT MESS WITH THE CHOKE AT ALL UNTIL THE WARM RUNNING ISSUES ARE RESOLVED. Doing so now will only compound the issues you now have. These smog engines are built to run lean, and a rich condition is more likely to cause poor performance than a lean one. Let me know... Ray
Hi guys, to give an update... I replaced the carb with a rebuilt carb and the car now runs great check engine light is on, but i suspect the carb needs to be tuned to my car. Performance wise, no problems Thanks for all your help
Matt, Remember that, as long as the check engine light is on, the engine will not perform to its max, due to the computer's programming. Anytime there is a problem, the computer fixes the dwell for the mixtures, and fixes the timing. Both if these issues will create less than optimum performance. If you provide the codes, I can help you fix them. I still suggest that you purchase a dwell meter, as it will provide invaluable info on the engine's tuning. That is what the green connector close to the carb is for. Let us know... Ray
