PhilbertZ Posted October 4, 2009 Share Posted October 4, 2009 Hi guys, I'm looking to replace my thermotime switch, as I've failed smog and the switch tested bad when I was going through the FSM troubleshooting checklist (my guess is that it doesn't work and the cold start valve is churning extra fuel into the engine, even when it's "warm".... Problem is, I can't seem to find the darn thing online! I've gone local to my autoparts store and they don't have it and cannot order it. I've searched at RockAuto, and Summitracing - no parts! I did more searching online and came up with this great page: http://market.autopartsfair.com/nissan-engine_parts/280-1983-fuel_injection-c4010_12906bos_3.html ....But I cannot order from the page/cart - it's like it's a phantom page teaser! I've searched everywhere online and come up with a ton of stuff for SAAB and others (using BOSCH parts), but the part numbers are different from the one I found on the "Phantom" site above. here is an example of a search result: http://www.google.com/products?q=bosch+thermo+time+switch%2C+280&aq=f Does anyone know if this is a pretty generic BOSCH part that will work with my S130 as well? I think the BOSCH connectors are the same (I Bought a bunch to replace my old connectors on my injectors, cold start valve, etc...).... Please help me find this so I can (hopefully) finally pass smog! Thanks in advance! Phil Quote Link to comment Share on other sites More sharing options...
eec564 Posted October 4, 2009 Share Posted October 4, 2009 The cold start injector should only squirt fuel while cranking with a cold engine. It doesn't keep adding fuel once the engine is running. You can verify this by checking for voltage at the connector for the valve itself, see if it has power with the engine off (key on), while cranking (remove coil wire) and while running. How and where did you test the switch you found to be bad? Did you unhook the cold start valve from the harness before testing? How badly are you failing smog and in what catagory(s)? Make sure your plugs aren't fouled and your o2 sensor is in good shape. These cars seems to go through those at a decent rate, especially if you spend a significant amount of time at WOT. Either way, FAST says the p/n for the 7/78-8/81 thermotime switch is 22635-N4710. Try the dealer, or see if someone can cross that number. -Eric Quote Link to comment Share on other sites More sharing options...
PhilbertZ Posted October 5, 2009 Author Share Posted October 5, 2009 Thanks Eric. I've got a thread already on my efforts - see here: http://forums.hybridz.org/showthread.php?t=151866&page=2 I'm following the FSM's tests for the EFI system using my ohmmeter and done most of them I think. The O2 sensor was replaced a month ago, along with wires, plugs, cat, cap and rotor. Did valve adjustment and timing after all that too. I have failed twice this summer, with high O2 and HC levels - see other post linked above for numbers. When doing the thermotime switch test, I disconnect the battery, starter ground and cold start valve (and O2 sensor) before checking continuity (hot and cold). It works at cold levels, but when the engine is warm, it's giving the same continuity as when it's cold, which means (I think) that it's telling the cold start valve to keep dumping fuel into the intake even when the engine is nice and warm (leading to my rich environment). The cold start valve works from what I can tell through testing - it squirts has when I hook it up manually to the battery (using the FSM test methods). I have not tested the car at the smog station with the new cat yet - I want to replace the thermotime switch, do one more timing/valve adjustment, and then take it in. Thanks for the part number-I'll see if I can track it down. I'm hoping there's a "generic" part that I could use, since this car seems to use a lot of BOSCH parts that other makes/models used (SAAB being one of them, with the connectors I got recently). Cheers, Phil Quote Link to comment Share on other sites More sharing options...
eec564 Posted October 5, 2009 Share Posted October 5, 2009 Wow, there's a bunch of wrong information in that thread. Also, the cold start valve only gets power when the engine is cranking. It doesn't matter what the thermotime switch is doing once you release the key, since it provides a ground signal to the cold start valve, and positive comes from the ignition switch. There isn't any time at all the valve should continue to operate once the motor is started. With the motor running, you can verify this by removing the plug for the cold start valve and testing for power on it. Also, pull your plugs and look at them. Look up articles on how to read plugs, and see what they're telling you. -Eric Quote Link to comment Share on other sites More sharing options...
PhilbertZ Posted October 5, 2009 Author Share Posted October 5, 2009 Thanks Eric - I'll check out my plugs and do more research on what they tell me. Can you elaborate a little on the misinformation? A PM would be great, or if you want to chime in on that thread to keep in on topic and help others in the future with similar issues? Thanks for clearing that up on the thermotime switch - so, basically if the engine is warm (77 degrees or warmer), and you're starting it for the first time, the cold start valve doesn't do anything (engine just starts with 6 injectors doing their normal job)...but if the engine is below 77 degrees when starting it up, the cold start valve "helps" by injecting some extra gas into the intake - but only when cranking? This would mean, even if the thermotime switch were faulty, I wouldn't be getting any extra gas put into the engine while it's running (after cranking at start), right? Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted October 5, 2009 Administrators Share Posted October 5, 2009 You live in Cali! Just delete the cold start injector! As already stated its function is during really cold starts, but we have found it is NOT required to start the engine even in colder climates, below freezing, and deleting it eliminates a potential fuel leak! The engine will start just fine without it. I have been deleting that injector on ALL of my Z cars, friends, and my customers Z cars since the late '80's and not one of those engines started any differently with it deleted. Quote Link to comment Share on other sites More sharing options...
eec564 Posted October 5, 2009 Share Posted October 5, 2009 Yup, that's right. Take a look at the EFI bible, you can pick up a copy from http://www.xenons130.com in the reference section, listed as the 280Z/ZX Fuel Injection Guide. Take a look at page 16, as well as the rest of the thing. I'll chime in on the other thread later, it'll take some thought and such, and I need to run out for a bit. In the mean time, read up on reading spark plugs. While there's more to it, a good start is here: http://www.dansmc.com/spark_plugs/spark_plugs_catalog.html -Eric [url=http://www.xenons130.com/files/280zfuelinjectionbook.pdf][/url] Quote Link to comment Share on other sites More sharing options...
PhilbertZ Posted October 6, 2009 Author Share Posted October 6, 2009 Thanks guys - I actually have the EFI bible already in hand - was using it initially for my ECU tests (and to learn about EFI for the first time) before using the FSM for the tests. I must have missed the part about the cold start valve only workind during cranking - sorry! I didn't realize I could delete it as well- do you guys have recommendations on the best way to do this that looks "stock" so i would pass visual inspection? I could snip the wires close to the plug on the cold start valve I suppose... I've been researching plugs since Eric's last post and the site you provided now is perfect. Most of the sites I've visited reference using new plugs and running on WOT to best diagnose the engine - but the plugs in the link Eric posted seem to be well used ones that I could just pull now to diagnose - am I correct in that assumption? I really wish there were an easier way to diagnose CO and HC mix without having to get smogged - I've been fiddling with this issue since I failed smog 2 months ago and now my registration is expired - would be nice to have a means to check my work to see if what I'm doing is working or not - I've done/replaced since then: - Cat - O2 sensor - Wires - Cap/Rotor - valve adjust - timing check (running stock timing marks) - Complete run of FSM ohmmeter ECU tests (thermotime switch failed) - new fuel filter Can you guys think of anything else I could change/test before taking it back to get smogged a third time? Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted October 6, 2009 Administrators Share Posted October 6, 2009 The simplest way to delete the cold start injector yet leave it for "appearances" sake is to deny it, fuel. Remove the fuel hose that runs between the fuel rail and the cold start injector, find a suitable hard plug that fits snugly in that fuel hose like a piece of aluminum or steel round stock in the 5/16" or 8mm range, (A long bolt will work, though you will want to cut off the head and the threads so you are just using the smooth shank, the plug doesn't need to be very long, maybe 1/2"+ in length), and work that plug up in the hose far enough so that you can reinstall the hose. Place hose clamp over the plug and tighten to be sure fuel wont get past it. Reinstall the hose, it will look totally stock, no fuel will get to the injector to be injected nor leak, you could even leave it wired up. Quote Link to comment Share on other sites More sharing options...
PhilbertZ Posted October 6, 2009 Author Share Posted October 6, 2009 Thanks BRAAP - that sounds easy enough to do. I think I'm going to take it in this weekend for my third smog attempt - I can't seem to think of anything else to change/test at this point, beyond what I've done in the past couple months (hopefully, adding the new cat since my second failed test will prove to have been the missing link). Thanks for your help guys - much appreciated! Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted October 6, 2009 Administrators Share Posted October 6, 2009 (edited) Thanks BRAAP - that sounds easy enough to do. I think I'm going to take it in this weekend for my third smog attempt - I can't seem to think of anything else to change/test at this point, beyond what I've done in the past couple months (hopefully, adding the new cat since my second failed test will prove to have been the missing link). Thanks for your help guys - much appreciated! If you are going through tail pipe testing, don't forget to be sure your ignition timing is at factory specs or even slightly retarded from that, you have a clean set of spark plugs in, plugs wires are also good/not too old. Poor ignition performance will cause subtle misfires, subtle enough you really can't hear them, but enough to fail smog tests. Typically the N/A Z cars run "noticeably" stronger with improved fuel mileage with the ignition advanced 5-7 degrees from the OE spec, but tends to kill the NoX when going through tail pipe testing. Edited October 6, 2009 by BRAAP Quote Link to comment Share on other sites More sharing options...
PhilbertZ Posted October 6, 2009 Author Share Posted October 6, 2009 If you are going through tail pipe testing, don't forget to be sure your ignition timing is at factory specs or even slightly retarded from that, you have a clean set of spark plugs in, plugs wires are also good/not too old. Poor ignition performance will cause subtle misfires, subtle enough you really can't hear them, but enough to fail smog tests. Typically the N/A Z cars run "noticeably" stronger with improved fuel mileage with the ignition advanced 5-7 degrees from the OE spec, but tends to kill the NoX when going through tail pipe testing. Thanks - I'll do that before I take it in. Plugs are newer (last 4,000 miles) but I'll get some new ones. So I'm clear, "advancing" the timing would mean, moving it from the factory spec 10-12 degrees BTDC to about 16-19 degrees before, correct? Quote Link to comment Share on other sites More sharing options...
eec564 Posted October 6, 2009 Share Posted October 6, 2009 Factory spec on my 82 NA is 8 BTDC. Try 11-12 to start with, and go gently from there. Quote Link to comment Share on other sites More sharing options...
PhilbertZ Posted October 6, 2009 Author Share Posted October 6, 2009 Factory spec on my 82 NA is 8 BTDC. Try 11-12 to start with, and go gently from there. I think I was off earlier in my post (meant 8-10 instead of 10-12) - don't have my FSM in front of me right now at work. I'll let you guys know how it goes - thanks again for all the information. Quote Link to comment Share on other sites More sharing options...
PhilbertZ Posted October 12, 2009 Author Share Posted October 12, 2009 (edited) Thanks everyone - I finally PASSED today - with flying colors! As mentioned in this thread and others, these are the steps I took to get the car in proper EFI order: New parts: - Cat - O2 sensor - Wires - Plugs - Cap/Rotor - new fuel filter Work/tests Done: - valve adjustment - timing check (running stock timing marks) - Complete run of FSM ohmmeter ECU tests (thermotime switch failed) - Plugged Thermotime switch hose with sheared and smoothed bolt - just in case) - New BOSCH eletrical connectors on injectors, thermotime switch, engine temp sensor (also cleaned off all connections with emory board and treated with dieletric grease) Got the car really hot on a freeway cruise before the test and it passed with the following levels: HC (PPM): 15 MPH: 210 (max allowed) 47 (actual on my car) 25 MPH: 178 (max allowed) 11 (actual on my car) CO%: 15 MPH: 1.35 (max allowed) 0.08 (actual on my car) 25 MPH: 1.15 (max allowed) 0.01 (actual on my car) Amazing how they contrasted to the original 2 failed tests I had. I think the CAT I installed after the second failed test was the real difference maker. Now here's my question: Now that I've passed and seem to know what to do to keep it in "Green" form, shouild I put the OEM (likely very clogged) CAT back on until the next test? I've heard the aftermarket California cats clog up fast, and I really don't want to shell out another $265 on this. Are there any performance gains/losses when using the old clogged cat, or just running a straight pipe where the CAT was? Where would I get this done (straight pipe CAT delete) if that's a good option? I don't drive the car much - less than 4,000 miles a year, but want it to be fun when I do.... Thanks everyone who has helped me on this project - really appreciate it! Edited October 12, 2009 by PhilbertZ accidentally hit "post" early...wasn't finished typing Quote Link to comment Share on other sites More sharing options...
eec564 Posted October 12, 2009 Share Posted October 12, 2009 Take a look inside your old cat. You should be able to see right through it, with a nice honey-comb. If you can't see light, then it's clogged and will eat power, if there's just a straight-through hole, then most likely retarded timing or running rich burned it out. If it looks physically in tact, then it's likely just old and worn out, but not damaged. Quote Link to comment Share on other sites More sharing options...
PhilbertZ Posted October 12, 2009 Author Share Posted October 12, 2009 Take a look inside your old cat. You should be able to see right through it, with a nice honey-comb. If you can't see light, then it's clogged and will eat power, if there's just a straight-through hole, then most likely retarded timing or running rich burned it out. If it looks physically in tact, then it's likely just old and worn out, but not damaged. I can see light through it but it's opaque - cannot see an abjoect through it. It looks like there's a screen door mesh material inside, with lots of soot caked on, and some light, far on the other end. My truck's is kind of the same way, and I need to get that smogged soon too (87 4runner). Hmmm...maybe they're the same size and fitment - swapping would be a nice option for smog Quote Link to comment Share on other sites More sharing options...
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