A friend of mine doesn't know who to go to for this, so he called me..I'm clueless, I gave it a guess or two but told him I wouldn't know where to begin. He doesn't have a Camaro, but I figure I might be able to give him at least a few ideas to bounce around for what could be wrong? Ok, it's like an 88 Plymouth Reliant..butt ugly. He hit the gas the other day at a stopsign...I thnk he said around 3/4 pedal.. He said the motor revved up, and dropped back down to idle speed and the car lurched forward. He hit the gas again, and again the motor revved and dropped back to idle (he wasnt releasing the pedal). He was a little freaked because there were cars all around him and he was lurching at idle speed across an intersection. I honestly don't know where to begin...but since it's an 88, it's got to be fuel injected, so....massive sensor malfunction? I've got the same sort of problem as him but a LOT less major and frequent. Any help or wild guesses would help. Thanks guys...he thanks ya too.

 

I didn't know those K-cars were fuel injected! I guess they had to be by then, though. I had a friend who had a K-car, her dad was always having to rebuild the carb... it would get carbon'd up and stick. I'd say to go over the major tuneup things, like cap, rotor, inspect the plugs, maybe do a resistance test on the plug wires (per foot, about 15,000 ohms), air filter, fuel filter, and especially timing. Give the vac lines a once-over, especially if it turns out to be carbureted. It might also be a dying alternator or battery...

 

It might not be FI, I really haven't even SEEN his engine... But I figured they'd go with the FI by 88, I mean that's a tad late to still be running a carb... Just talked to him....I'm trying to get him to get me a list of what he's already replaced..he said half of the stuff under the hood is new. As far as checking the plug wires, how would you do a test like that? Believe me, I know NOTHING about electronics. Drives me nuts because half of my replies to questions are like "get a multimeter and check your throttle position sensor..should read so-and-so". I can buy a multimeter and start touching it to stuff and staring blankly at it, but I won't have the slightest idea of how to use it! (I think I WILL buy one...Sears has them on sale right now)

 

I've seen Jerad's engine (the Relient). It is deffenently FI. And Nixon1... *** help you if you get a multimeter. Just joking man...put down the knife...

 

Ha ha.. The sale ended like 3 days ago..I'm so pissed. I could've gotten a $30 multimeter for $18. Howard...I'd spend the next week reading the manual OVER and OVER trying to figure out how to work the thing...heh...

 

What? A $30 multimeter for $18? You're kidding me! That's the worst deal I ever heard of!!! Why not get an $80 meter for $15?? That's right, go to http://www.sunpro.com . Click on "garage sale". Click on "Test & Tune". Click on the first item, "Digital Engine Multimeter - CP7676GS". Then go pick it up. WaynesRS managed to get a box with his; mine came in a cardboard shipping box, I don't know how he swung THAT deal, but original box or not, it's an awesome deal.

Multimeters just read voltage or resistance. This meter also has a tachometer reading if you want to use it. But: To measure voltage, you flip the switch to DC volts. Put the black probe on the negative of the battery, and touch the red probe to where you want to check voltage. For example, in my code 32 chart, step #1, you'd put the black probe on the neg of the car battery (or to the bare metal of the engine block or frame), and touch the red probe to terminal "B" of the harness connector. Simple! Remember to use volts DC (battery) instead of volts AC (house current), or you'll get a wacky reading.

For resistance, you flip the switch to ohms, looks like an upside down "U". Touch a probe to each end of the piece you're measuring the resistance of, then read the scale.

There's things called ranges. For example, you could have four VDC (volts, DC) settings: 5 VDC, 20 VDC, 100 VDC, 1000 VDC. What's it mean? It defines the accuracy of the readout. You can measure 4.5 volts on the "1000 VDC" scale- but it'll show as "4". Switch to the "5 VDC" scale, and you'll see 4.500.

For resistance, you could have settings of 100 ohms, 300 ohms, 1K ohm (K means 1000, so, 1000 ohms), 10K (10,000) ohms, 100k (100,000 ohms). So we know that stock plug wires are 15,000 ohms per foot. From now on, I'm calling that (properly) 15K ohms. You've got a wire thats 2.5 feet long, so we will expect 2.5 times 15K ohms, giving us 37.5K ohms. So we would use the meter at the 100K setting. See?

One point to make, on the previous example. Remember what I said about accuracy? Well, that 37.5 K ohms, which is really 37,500 ohms, will show up on the "100K ohms" scale as 37.5 - meaning, 37.5 k ohms, meaning, 37,500. I hope I made sense. If you get that meter (and ya should!) you'll see what I mean by playing with it.

As a basic rule, you can always use the highest range to measure a low voltage. But Never, Ever, try to measure a HIGH voltage with a LOW scale. Best case, the meter says "overrange"- basically, "hey buddy you're nuts." Bad case, the meter blows a fuse. Worst case, you cook the meter (usually doesn't happen).

So go get a meter. NOW! While you're at it, go get a sensor probe and fuel injector tester. Aw, dammit, they sold out of the pen meters. I was going to get a few for xmas presents (they were going for $8/apiece). Oh well! Funny how they never sold out of this stuff until I mentioned the sunpro site at the main tech board

So to check the plug wires, flip to the 100k scale. Take a wire off. Put a probe at each end, doesn't matter which probe goes to which end (resistance has no + or - polarity). Write the reading down, and take the probes off. Measure the length of the wire, and multiply the length by 15,000. If your wire resistance is really off, the wire is bad.

 

If I didn't feel totally gay even thinking about it, I'd give you an e-hug man! Heh..thanks..thats a HELL of a deal. I could use this sucker for a lot.. I'm ordering it tomorrow.... Maybe I can figure out if a sensor or two of mine is totally shot! OHH, and I can use it to compare the resistances of my old and new sets of spark plug wires and stuff.....see if this Belden stuff the shop puts on is better than my old Champions. I've heard Belden is premium wire but I've never seen it actually sold anywhere...

 

Question, Tom.. How do you know where to touch the red probe to check voltage on various sensors, etc? Is there a surefire way to always know, or is it more like 'touch it here, if the reading doesnt make sense, try it over here instead'?

 

An e-hug?!? If you did that I'd have to give you an e-punch, so don't even try it! And, usually you'd be using a manual that tells you where to probe, like my GM Service Manual http://www.helminc.com . Some sensors might have a fit if you probe them the wrong way. But that's what's good about the meter I showed ya; it's got a 10 MegOhm Input Impedance. What that means is, the meter doesn't suck a lot of power when it takes a measurement.

For example, the ECM circuitry is mostly "flip-flops", an electronics term for a semiconductor that's either On or Off. These things don't put out much current, it's in the milli-amps, and if you try to draw large current thru 'em, you'll burn them up. One example is an analog meter, with the needle and the scale. Those things will draw too much power through the ECM driver circuitry, and burn up the ECM. With the digital meter, it doesn't suck a lot of power, and basically, because of the 10 MegOhm Input Impedance, the ECM won't even notice the meter's there. 10MOhm is a large resistance. Some quick physics... infinite resistance is very high. In fact you can measure infinite resistance with your new meter. Turn the meter to ohms, and don't put the probes to anything. That's infinite resistance- no path to electricity. The opposite of infinite resistance is zero resistance, which is measured by touching the two probes together. (This has to be done on analog meters to "zero" the meter's pointer.) So 10 Meg Ohm is so large, it's faking an infinite resistance, and the computer won't even notice it, because to the computer, you might as well not have hooked up any meter! Did that make sense? If it didn't, just ignore it all... not important. Our skin has resistance to it, which is why we can get shocked. Turn the meter to ohms, put the two probe tips close together but not touching, and then squeeze the tips between your finger and thumb. You'll see the resistance on the meter. 'Fact, by knowing the resistance of the human body, you can calculate how much electricty it takes to kill someone. (We did that in Physics, too.) I still remember the drawing that the professor put on the board... he drew a stick figure connected to a power source, then we did V=IR (ohms law).

Oh, but most things, you don't even need a book. Say you're diagnosing a bad fan switch because your fan doesn't come on. We know the fan switch "closes" at 230 degrees. (If you know this already, stop me, but: By a switch being closed, I mean it's on. When a switch is "open" it's off. Think of measuring resistance again. Probes are "open" = away from each other, no resistance reading. Probes are "Closed" = touching = the meter gets a reading) So you could bring your motor up to 230 degrees, and turn it off. Then unplug the fan switch sensor wire, flip the meter to voltage, and probe between the fan switch and the positive of the battery. (so black terminal to center of fan switch sensor in the back of the passenger side head, and red probe to the + of the batttery) We put negative to the fan switch because the fan switch grounds to the engine block. So since you brought the motor up to 230 degrees and shut it off, that motor's gonna be HOT (and probably go past 230 degrees when it's just sitting there, turned off), so the fan switch will have closed. Do the probe, and you should see 12 volts at the meter. Stuff like that. The GM manual helps out a LOT!

 

If you e-punched me, I'd just have to e-shove my e-boot up your e----nevermind. Thanks again Tom...you should be the board tutor. Professor Tom...I think it fits. Get a doctorate. I ordered that multimeter today..and it shipped out today. Hell yes... Bought my cap and rotor set today too, along with plugs. I went with the Blue Streak cap and Bosch Platinum plugs. Those 4 pronged platinums were EXPENSIVE as hell, like $5 per plug, I just went with the regulars...

 

Yeah, once you measure a few things with the meter, you'll get the hang of it. You'll also see how the different range selections (like volts DC ranges) work. You could measure resistance of your MAT (IAT) temp sensor in the airbox, measure resistance of the coolant temp sensor, adjust the throttle position sensor (85-89 2.8's only), check oxygen sensor voltage, even check to see if your alternator's charging the battery properly (with engine running, voltage at battery should be 13.8). Combine your meter with a $6 set of alligator clip jumpers from Radio Shack, and you won't have to worry about holding the negative probe to ground; you just have to move the red probe. Here's a radio shack link: http://www.radioshack.com/product.as...5Fid=278%2D001 It's a set of 4 wires, red/yellow/green/black, for $4.

And haha, I could never stay in school that long... er, well, if I didn't "have my fun", I could've had a doctorate by now. That's alright, at least I'm back in. (sigh)

 

Heh...I'm on the community college plan myself. Once I graduate high school this year, I'm probably taking a year off and then going into the community college..gonna major in film.. Make big bucks, get myself a 3rd gen 350 IROC, keep this car, and mod the **** out of both of them. This'll be my daily.. Well, that's my IDEAL plan anyways.....