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#1666 of 1692 Re: Sensor Voltage Weirdity [shaggyman1] by zaken1 Aug 20, 2009 (9:39 am)
Replying to: shaggyman1 (Aug 20, 2009 6:46 am) Well; it sounds like the time for a little more education: The supply voltage in any series electrical circuit will ALL be dropped across the sum total of the resistances of the loads in that circuit; regardless of how much or how little resistance there is in the circuit. The amount of voltage drop across any single element will be proportional to the percentage of the total circuit resistance which it constitutes. Regardless of whether there is one, or six, or one hundred resistive elements in a 12 volt circuit; the entire 12 volts will always be dropped across the whole circuit. Suppose there are six resistive elements in a particular series circuit. If each of those six loads have the same amount of resistance; then each element will drop 1/6 of the total circuit supply voltage (which works out to 2 volts drop across each element). If there is only one resistive element in the circuit; then the entire 12 volt supply voltage will be dropped across that one element (regardless of whether the resistance of that element is 1/10 ohm, 5 ohms, or 10,000 ohms). If there are unequal resistances in a series circuit; then the supply voltage will be dropped across those loads in proportion to their resistances: Suppose there is a 5 ohm and a 10 ohm load in series with a 12 volt supply. In this circuit, the total circuit resistance is 15 ohms. The 5 ohm load makes up 1/3 of the 15 ohm total circuit resistance; so it will drop 1/3 of the supply voltage (which works out to 4 volts). The 10 ohm load makes up 2/3 of the 15 ohm total circuit resistance; so it will drop 2/3 of the supply voltage (which works out to 8 volts). 4 volts + 8 volts = 12 volts; which makes this a legally functioning circuit, because the entire supply voltage is used up.   I hope you can see from this that the voltage drop across a 3 ohm load has NOTHING to do with the amount of resistance of that load. It is solely determined by how much ADDITIONAL resistance is in series in that circuit. If the 3 ohm heater is the only resistance in that circuit (which is what I would expect in a heating circuit) then the entire 12 volt supply (minus what is dropped across the plugs and wiring harness) will be dropped across that 3 ohm resistance. Applying Ohm's Law (Current = Voltage divided by Resistance); 12 volts / 3 ohms = 4 amps. 4 amps current at 12 volts is 48 watts of power (Power = Voltage X Current). 48 watts of power is about what a single 12 volt headlight draws. That is not at all unreasonable for a heater that has to bring a steady stream of fuel and air up to a temperature high enough to vaporize the fuel. It probably sounds high to you because most other current draws in automotive electronics are much smaller than that. But I expect the rear window defroster grid draws at least that much. And the starter motor draws 20 to 30 times that much!!! So your test of the EFE heater tells me that it is working right.   I appreciate your perception that this appears to be a temperature sensitive problem; but I assure you that the root cause will turn out not to be someting directly related to temperature, and will instead turn out to be related to excess leanness, or sudden changes in air/fuel ratio when the throttle is opened. I'm glad you tested the TPS and eliminated that as a potential cause. I can accept that; and this information helps narrow down the focus.   What it now sounds like to me is that the EGR valve is opening too soon, or too suddenly, when the throttle is opened. This would happen if one or more of the EGR vacuum control devices were bypassed or missing. (there should be an exhaust back pressure tradsducer and an electrical vacuum switching solenoid in the vacuum lines to the EGR valve). It would also happen if the ignition timing had been adjusted without first disabling the electronic advance by shorting the check connector wires.
#1667 of 1692 Re: Sensor Voltage Weirdity [shaggyman1] by zaken1 Aug 20, 2009 (11:08 am)
Replying to: shaggyman1 (Aug 20, 2009 6:46 am) In addition to improper EGR valve regulation (the EGR valve essentially acts as a massive timed vacuum leak into the intake manifold), two other vacuum related issues would be a vacuum leak in the hose to the brake booster from the intake manifold, or the use of the wrong model PCV valve, or a PCV valve that was not plugged into its socket. An additional EGR issue could come from using manifold vacuum, or the wrong throttle body vacuum spigot, to supply the EGR circuit (it should come from the spigot on the front of the throttle body which is closest to the passenger side). A purge circuit issue could be caused by using manifold vacuum or the EGR spigot to supply the purge control valve (it should come from the port on the front of the throttle body which is closest to the driver's side).   You can eliminate the EGR valve as a factor by simply disconnecting and plugging its vacuum hose; and seeing if that changes the stalling behavior. However; the EGR valve may also be sticking partly open; and may thus never close fully. And that would continue whether the vacuum hose was connected or plugged. It should be possible to reach underneath the valve actuating diaphragm, and manually raise and release it to see whether the spring returns it all the way down. If you manually raise the valve while the motor is cold and idling; it should make it stall.   And if none of these things work, it is probably time to reset the dreaded idle air bypass.
#1668 of 1692 check engine light flashing by shaggyman1 Sep 17, 2009 (2:07 pm)
96 Metro 1.0/5spd Check engine light flashing occasionally while driving. Flashes for a couple minutes, then reverts to steady on for a while, then starts flashing again. Does this indicate it is busy setting a code? Is the brainbox freaking out? I'm currently getting a fairly frequent #1 cylinder misfire code, but I've never seen the light flash while driving before. Don't find any mention of this in forum archives or in manuals.   Currently have bad compression in #1, and am waiting on parts to arrive to do a ring and valve job. Hopefully I won't have to replace the ECU too. Replies to this message: zaken1 (Sep 17, 2009 6:21 pm) zaken1 (Sep 18, 2009 8:27 am)
#1669 of 1692 Re: check engine light flashing [shaggyman1] by zaken1 Sep 17, 2009 (6:21 pm)
Replying to: shaggyman1 (Sep 17, 2009 2:07 pm) My check engine light has flashed on occasion; when the air/fuel mixture was too lean in one particular load range; but was OK at other loads. What you describe sounds pretty normal; particularly considering the low # 1 cyl compression. I would expect it to go away after the compression is fixed. I seriously doubt that there is a problem with the computer.
#1670 of 1692 Re: check engine light flashing [shaggyman1] by zaken1 Sep 18, 2009 (8:27 am)
Replying to: shaggyman1 (Sep 17, 2009 2:07 pm) I just wanted to add that when one of these motors reaches the point where it is leaking compression past the pistons; just replacing the rings is often not enough to fix it. The reason for this is that a major part of the leakage takes place from the ring gooves in the piston becoming enlarged by wear. And that leads to compression leakage on the inside edge of the rings, through the ring grooves. In addition, when the ring grooves become worn; the increased clearance erodes the support the grooves normally provide to the rings; which allows the rings to twist and flex. And that raises havoc with the seal between the rings and the cylinder wall. So the right way to fix the problem is to replace both the rings and pistons; once it has been determined that the cylinder bores are still straight enough to support new pistons.   These little motors make much more economy and power for their size than an old Ford flathead or Chevy 6; and as a result they are far more critical and demanding about precision in mechanical tolerances and tuning adjustments.
#1671 of 1692 Same Bug after rebuild. by shaggyman1 Sep 25, 2009 (10:31 am)
96 1.0/5 Valve job, rings, bearings. Compression test shows 200 in all three. Replaced: MAT, Distributor, Coil, Cap/rotor/wires/plugs, PCV and Throttle body with TPS, Injector, Fuel Pressure Regulator, ISM. Thoroughly clead all carbon from pistons and EGR tube in intake manifold.   Set a code for EGR flow after 40 miles- had the vacuum lines reversed on the modulator (the label on mine was gone). Just to be sure, I replaced all the vacuum lines, the modulator, and both the solenoid valves.   Runs great, except for two problems: 1. Cold starts are the same as on the last engine/TB, etc- will not accept ANY throttle without dying until warmed up. ( I now suspect either the TPS, which is a three wire without an idle switch in it) or the fuel vapor purge system, which I find difficult to fathom. I just don't want another burned valve in a couple thousand miles....   2. Air in the cooling system- this one REALLY scares me, as I don't seem to be able to clear it out. It will idle warm with an occasional bubble in the radiator filler neck, but when I race the engine, I get lots of bubbles, with an occasional surge- as if there were a pocket of steam forming somewhere and suddenly venting with the increased flow. The bubbles do not smell like exhaust, and there is no greasy film on top of the water (haven't put antifreeze in yet, as I don't want to waste it). Could this be a failing water pump, or is it more likely to be a cracked block?   Is there a flow spec for the water pump? Some kind of sniffer for the cooling system? Replies to this message: zaken1 (Sep 25, 2009 12:07 pm) shaggyman1 (Sep 25, 2009 1:14 pm)
#1672 of 1692 Re: Same Bug after rebuild. [shaggyman1] by zaken1 Sep 25, 2009 (12:07 pm)
Replying to: shaggyman1 (Sep 25, 2009 10:31 am) You say you replaced all those parts; but were they new or used replacements? If they were used; there might be compatability issues. And even if they were new, there still might have been errors in listings or model selection. There were significant changes in the TPS and distributor over the years. I tend to feel that you still don't have the right TPS. Also; the distributor for the 1996 model should not have a vacuum advance. If it is the right type (made for electronic advance, rather than vacuum advance) the timing MUST be set with a strobe while the check connector terminals are shorted to disable the electronic advance. Otherwise your timing will end up too far retarded.   Does your engine have an electrical EGR vacuum switching valve unit in series with the exhaust back pressure transducer? If the VSV is not in the circuit; the EGR valve will get far too much vacuum; which will create all sorts of undesirable leanness. Do you have a vacuum hose routing diagram, so you can be sure the hoses are correctly routed?   Regarding the evap cannister purge; the purge control valve on top of the cannister (at least on the earlier models) is activated by a vacuum signal from the purge port on the throttle body. There is some sort of temperature sensing "wax valve" plumbed into that vacuum line; which bleeds air into the signal line when the engine is cold, to reduce the strength of the vacuum signal to the purge control valve. If that air bleed function is defeated; it would result in the purge valve opening when the engine is cold; which would cause severe hesitation.   On the earlier throttle bodies; there are three vacuum spigots, coming from ports which are all located at slightly different heights. The spigot closest to the distributor is intended for the purge system. The port which supplies that spigot is the highest of the three on the throttle body wall; which means it will be the last one to supply vacuum as the throttle is opened. The spigot furthest from the distributor is used to supply the EGR vacuum signal. It is the lowest (earliest opening) of the three ports. And the spigot in the middle was used to supply vacuum to the distributor advance (on those cars with vacuum advances). That spigot is typically capped on cars with electronic spark advance. If you get vacuum from the wrong spigot; it can really mess up the engine operation, particularly with regard to setting EGR codes.   Have you tried setting the heater temperature valve control to maximum heat; in order to purge all trapped air from the heater core? And do you have a thermostat installed in the cooling system? Running without a thermostat can create weird imbalances in coolant flow. You can check for pressure build up in the cooling system with a radiator pressure tester. Install the tester in the filller neck, and pump up just enough pressure to lift the needle off the peg. Then start the engine while it is cold; and watch the pressure gauge. There should be no significant increase in pressure for at least the first 5 minutes of running (or until the temperature gauge reaches normal and the thermostat opens). Replies to this message: shaggyman1 (Sep 25, 2009 1:14 pm)
#1673 of 1692 Re: Same Bug after rebuild. [zaken1] by shaggyman1 Sep 25, 2009 (1:14 pm)
Replying to: zaken1 (Sep 25, 2009 12:07 pm) Most of the RPL parts were used, but bench tested okay. All of the TPS units (5) are the same- 3 wires, same as my harness. Input Voltage from ECU, Signal to CPU, and ground. Signal always goes through the potentiometer.   Distributor is correct- with no vacuum advance and the pickiup coil bench tests okay.   EGR is a bit different: Vacuum from TB base goes to a VSV, which goes to the "P" side of the modulator. The "Q" side of the modulator goes to a second VSV, which controls actuating vacuum from another spigot on the TB, which is connected to the EGR through this second VSV. All connections are true to the diagram on the hood.   The third and lowest spigot goes to the purge system. I think I will try plugging the line to the purge system and see what it does to a cold start.   I have a new thermostat which functions as expected, and have "burped the system from the high point on the back of the TB. Spot on with the pressure check- I hadn't thought about it in that way. If the engine is cold, there should be no increase in pressure until the coolant starts warming up, so an increase would have to come from combustion gasses leaking into it. I sure hope not- I really don't want to tear the whole thing down again. Sigh. At least I have a couple other blocks to start with, and might as well jump on whichever one has cylinders in better shape. (BTW, the piston ring grooves appeared to be undamaged, although I didn't bother to mike them- I was hoping for a quick 'n' dirty rehabilitation, not a perfect remanufacture)   Thanks for the good advice....
#1674 of 1692 vacuum hose routing by offshore3 Sep 29, 2009 (5:15 am)
I have a 1996 geo metro I am restoring and the vacuum hoses are missing. Its a 1.3 liter. Does anyone have a diagram of these hoses? Thanks
#1675 of 1692 95 metro : wont idle will run other wise by leadfoot429 Oct 01, 2009 (12:32 pm)
I have 95 metro 1.0 engine with manual 5 speed it starts and runs as long as i give it gas and drives normally. just replaced fuel regulator had head done a few weeks ago ran fine for a week then this O2sensor gave readings of .4- to 1.2 volts seams a little high since most i read say up to 1 volt TPS was smooth resistance from bottom of reading to top dont remember what the readings where exactly idle control motor is working after took it off and cleaned it and surrounding stuff. also the fuel milage has dropped 5-7 mpg since head gasket was done not so much worried about that as the wont idle (dies every time come to stop sign) since i drive 55 miles to work then same home kind of pain driving it this way i am new here so any help would be appreceated() Replies to this message: leadfoot429 (Oct 01, 2009 12:33 pm) zaken1 (Oct 01, 2009 8:17 pm) leadfoot429 (Oct 02, 2009 2:31 pm) zaken1 (Oct 02, 2009 7:37 pm) and 2 more...

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