Hi all, new member here. Just bought a 1990 V6 Extended cab pickup over the weekend. It ran fairly well when I bought it, save for a leaky exhaust manifold. Saturday I started a tune-up...changed the oil, put on new cap and rotor. When I started it back up it ran like crap. Would barely idle, didn't want to throttle up. Exhaust smells REALLY rich. I've started going thru some troubleshooting steps, checked all the vacuum lines, and checked the troubleshooting codes in the ECU. ECU is only giving me code 55, so no help there. I pulled the coil, and the primary resistance is 1.4 ohms. The manual gives a range of 0.7 to 1.0 ohms. Would 0.4 ohms out of range cause it to run very rough like that?
Any other suggestions are welcome. I'm at a loss. All I did was install new cap and rotor and change the oil. Afterwards I went ahead and replaced the plugs too. It had Bosch +4s installed and I've never been a big fan of them. I correctly gapped the new plugs and am getting spark to each plug. Just wondering if it might be a weak coil. Thanks.
Hi all, new member here. Just bought a 1990 V6 Extended cab pickup over the weekend. It ran fairly well when I bought it, save for a leaky exhaust manifold. Saturday I started a tune-up...changed the oil, put on new cap and rotor. When I started it back up it ran like crap. Would barely idle, didn't want to throttle up. Exhaust smells REALLY rich. I've started going thru some troubleshooting steps, checked all the vacuum lines, and checked the troubleshooting codes in the ECU. ECU is only giving me code 55, so no help there. I pulled the coil, and the primary resistance is 1.4 ohms. The manual gives a range of 0.7 to 1.0 ohms. Would 0.4 ohms out of range cause it to run very rough like that?
Any other suggestions are welcome. I'm at a loss. All I did was install new cap and rotor and change the oil. Afterwards I went ahead and replaced the plugs too. It had Bosch +4s installed and I've never been a big fan of them. I correctly gapped the new plugs and am getting spark to each plug. Just wondering if it might be a weak coil. Thanks.
It could be but not likely since it was fine before this and you didn't remove it. I'd look to make sure you put the cap on the right direction and that the wires aren't frayed, try looking at the wires while the hood is just barely open while its running and look for a blue spark if one is seen then your wire is grounding out to the engine and you need to replace them. Also any Bosch plugs shuldn't be qualified as an automotive part, I know first hand of the Bosch devil and his evil ways . I'd let my grass grow ten feet tall before I put a bosch plug in my mower even! Whatever is wrong is becasue of something you did or didn't do, stuff just doesn't break right after you tune it up unless its a Honda. Oh also check the fuses/fusible links for one that may have burned up.
Last edited by nissanjunkie : Jul 19th, 2004 at 05:34 PM.
I checked the wires last night while it was dark and didn't see anything...I'll go through the fuses next. Are there any I should be checking besides the ones under the dash?
I'd look at the fusible link(s) that are about an inch or two away from the battery on the pos cable too. The grounds should all be removed and cleaned if you don't find a bad pos wire. If you have a digital volt meter (you can get a cheap one just don't use it to check ohms) then I'd check the battery voltage (12-13 volts is normal) and its water level too. I'd also see how many volts the alternator is sending to the battery when its running (13-14 volts is about standard and no less than 12 is a good rule to go by). And lastly the .4 ohms difference may not be accurate if you don't have an expensive?accurate meter (fluke 88 mechanics meter cost $300 or so but its super accurate). Another BTW How do you know your geting spark to each plug? If you didn't use a spark plug wire tester then you cant be sure they are getting enough spark I can tell you how to make one if its needed. And lastly, this time for real, check the resistance on the spark plug wires they will be about 20,000 ohms if they're ok and you'll see the OL on the display if they're bad or open.
I'll check the resistance on the plug wires and the battery voltages.
Here's a stupid question...where's a good place to check vacuum? I pulled the line going to the canister on the driver's fender and also pulled the one going to the air intake snorkel. Neither had any vacuum.
Here's a stupid question...where's a good place to check vacuum? I pulled the line going to the canister on the driver's fender and also pulled the one going to the air intake snorkel. Neither had any vacuum.
That's not a stupid question at all. You have to check vaccum on a line going to the intake side of the engine like the EGR valve or the hose going to the brake booster. I'd probly check the egr hose if I needed to do that since its easy to find but any hose on the intake side will work. Going to cut grass but will be on at 10 if further info analysis is needed. BTW I charge by the hour so I'm gonna put you on a tab! J/K!!!! I couldn't ever charge for advice on Nissans since the goverment (and hence to a lesser extent you) paid for my automotive training.
Well...voltage from the battery is 12.4, 13.6 from the alternator with the eng idling. The plug wires seem ok, resistance ranged from 5k to 10.7k ohms. Ran the engine in the dark, didn't see any arcing from the wires. One thing strikes me as odd: there's no vacuum to the EGR valve. The only line I checked that had any vacuum at all was the brake booster line. Dunno if that's significant or not. This thing is really stumping me.
It ran ok before you did the tune up, but badly after.
Logic dictates that you screwed something up.
Look carefully at those plug wires and that distributor cap, maybe you got a wire mismatched, or you got a bad cap etc.
I've gone over the wiring about 10 times. I tried putting the old cap and rotor back on, it made no difference. I think I'll go get a new set of wires tomorrow. I can't see them arcing, but maybe they're arcing down inside around the plug boot. Or maybe the connectors are just spread and not making a good connection.
Well...voltage from the battery is 12.4, 13.6 from the alternator with the eng idling. The plug wires seem ok, resistance ranged from 5k to 10.7k ohms. Ran the engine in the dark, didn't see any arcing from the wires. One thing strikes me as odd: there's no vacuum to the EGR valve. The only line I checked that had any vacuum at all was the brake booster line. Dunno if that's significant or not. This thing is really stumping me.
Battery and alt numbers are good as well as the plug wires and resistance was up to 20,000 ohms, my bad on the wire specs. The EGR only comes on when the engine is fully warm and the computer is in closed loop, my bad again. What was the vaccum reading on the brake booster line? You can check the intake manifold for a manifold leak if the vaccum is low by spraying some starting fluid around where it and the head join while its running. Check the rotor button to make sure you have it in right, the same goes for the cap. I put mine on backwards when I had my sentra. Also you may want to check the timing, you might have threw it off a little while putting the cap back on.
From looking thru the Haynes manual I got the impression that the timing was computer controlled on the 1990 V6. Am I wrong? Because that's almost exactly what it seems like, out of time.
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. I'd let my grass grow ten feet tall before I put a bosch plug in my mower even! Whatever is wrong is becasue of something you did or didn't do, stuff just doesn't break right after you tune it up unless its a Honda. Oh also check the fuses/fusible links for one that may have burned up.
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