Connor280ZX Posted September 16, 2014 Share Posted September 16, 2014 After i installed the new ICM on my car, it ran great... for about a week. Today, first off the car felt very sluggish to accelerate, and struggles to climb hills. In traffic i noticed the tach needle started jumping around a few times. Then, once i had to accelerate going on to a highway at WOT, above 5000 RPM the engine would hardly accelerate anymore, and start to surge like hitting a rev limiter. Once i got home, i checked all of my electrical connections. Checked the ignition timing which showed 10 BTDC. My guess is that this chinese ICM that i bought is bad, but let me know if you think otherwise. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 16, 2014 Share Posted September 16, 2014 Fuel Filter. FYI, you won't get acceleration on a stock L28 much above 5,000 owing to the fact peak power is at 5,300 rpms. I am guessing "ICM" is "Ignition Control Module"? Quote Link to comment Share on other sites More sharing options...
Connor280ZX Posted September 16, 2014 Author Share Posted September 16, 2014 (edited) I guess i could try replacing that. It's only 10,000 miles old, but i do run my tank down every now and then. Sometimes surges at that RPM when revving in neutral BTW. Yes, i am referring to the ignition module. I usually shift around 5.6-5.7K. It pulls, or pulled nicely untill it starts to choke around 5,800. Edited September 16, 2014 by Connor280ZX Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 16, 2014 Share Posted September 16, 2014 There are eleven ignition system tests that you can do using a meter, page EL-28. You might also check the stator magnet to see if it's broken, check the air gap, check that the bushings aren't worn allowing the air gap to change. Look at the tips of the six point reluctor for signs that they've been touching the stator. Pretty common I think for the magnets to break and the bushings to wear out. The bushings are available as a maintenance item. Someone posted recently also about another part that wears, but I can't remember what it is. Might not find your problem, but you'll know more than you do now. On fuel - there's always the old gauge sticking from the hood method. Watch what happens in the problem zone. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 16, 2014 Share Posted September 16, 2014 Nice to add more information. The FSM is your friend on basic maintenance issues. Quote Link to comment Share on other sites More sharing options...
Connor280ZX Posted September 16, 2014 Author Share Posted September 16, 2014 Ok, thanks for the tips guys. Forgot to mention it is a rebuilt dizzy that i installed 5,000 miles ago for the reason Zed stated above. I'll replace the filter, and look up the tests for the dizzy just incase. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 16, 2014 Share Posted September 16, 2014 Oh, rebuilt 5K ago as well? good info to know. "In traffic i noticed the tach needle started jumping around a few times." Hint: What drives the tachometer (assuming it's good and not failing)? What component gives the tachometer its input to twist the needle? And what component triggers it? And what component triggers it? Quote Link to comment Share on other sites More sharing options...
Connor280ZX Posted September 16, 2014 Author Share Posted September 16, 2014 As far as i know, the tach signal comes from the ICM, and the tach has influence on the ECU or something. Correct me if i'm wrong. Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 16, 2014 Share Posted September 16, 2014 (edited) Wring diagrams in the back of the EL chapter. Nissan did a poor job on it though, trying to show turbo and NA on one drawing. Still figurable. You are wrong (you requested). Edit - actually you're only partially wrong. Edited September 16, 2014 by NewZed Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 16, 2014 Share Posted September 16, 2014 The signal comes off the (-) terminal on the coil, and yes, it's controlled by the Ignition Module (it really doesn't control anything, it's a switching box that has a fixed dwell feature..."ICM" is not "Datsunspeak"...) If you have a tach freaking out intermittently, and it's good, then.....your input circuitry is giving a bad signal source to it. Quote Link to comment Share on other sites More sharing options...
Connor280ZX Posted September 17, 2014 Author Share Posted September 17, 2014 Alright then. I have a new module on the way, this time not Chinese made and with a one year warranty. Thanks for the help, all. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 17, 2014 Share Posted September 17, 2014 No thanks until its running right! Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 17, 2014 Share Posted September 17, 2014 (edited) One day and 12 posts later, no testing done, and you're buying new parts without knowing much more than when you started. Don't forget the coil itself. And if you're guessing on the module, the GM HEI module is a much cheaper way to go. It will wire up just the like the black box does. Edited September 17, 2014 by NewZed Quote Link to comment Share on other sites More sharing options...
Connor280ZX Posted September 17, 2014 Author Share Posted September 17, 2014 (edited) Of course I have ran some tests. Checked resistance of the unit, coil and voltage at coil. Not to mention that I have tried switching out the coils. I don't like the idea of wiring up an aftermarket IGN system on my daily driver, so I bought a direct replacement. Edited September 17, 2014 by Connor280ZX Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 18, 2014 Share Posted September 18, 2014 (edited) A GM HEI is not exactly an 'Aftermarket' system, it's just what another OEM uses. I have run an AFTERMARKET performance GM HEI since 2002, I can shoot a spark almost 4". Try that with a stock E12-80! It cost me a whopping $48 too... There are 'direct replacements' and there are performance improvements which sacrifice no reliability. The GMHEI module swap is one of them. Plus, the "TACH" terminal on the GM module comes in handy....for something...I forget what... Edited September 18, 2014 by Tony D Quote Link to comment Share on other sites More sharing options...
Connor280ZX Posted September 20, 2014 Author Share Posted September 20, 2014 (edited) Alright, it's been a couple of days since I've installed the new new module, and the car is running very well. However, there's now a small issue. Whenever I let off of the gas when the car is moving, the tach needle jumps down, maybe 300-500 Rpm, but immediately recalibrates. Edited September 20, 2014 by Connor280ZX Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 21, 2014 Share Posted September 21, 2014 "Whenever I let off of the gas when the car is moving, the tach needle jumps down, maybe 300-500 Rpm, but immediately recalibrates." Look for a pinched wire, begging the obvious logical response of "when you take your foot off the gas pedal the tach needle SHOULD 'go down' and continuing thereforth..." Quote Link to comment Share on other sites More sharing options...
Connor280ZX Posted September 21, 2014 Author Share Posted September 21, 2014 Oh, right, should have structured that sentence better. A better example: Cruising, 4th gear at 2700 RPM, i'd let off the gas for a split second (without losing ANY speed) and this would occur. I'll check my wiring. Quote Link to comment Share on other sites More sharing options...
Connor280ZX Posted September 21, 2014 Author Share Posted September 21, 2014 Update: car is dying. Now I am getting a heavy misfire under more than light acceleration. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 21, 2014 Share Posted September 21, 2014 Alternator dead driving on a dying battery? Quote Link to comment Share on other sites More sharing options...
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