silver280zx Posted November 13, 2008 Share Posted November 13, 2008 I have a 79 s130 and i just replaced the intake/header gasket, and it was like a kind of paper gasket. I torqued it to the 15 lbs that the manual recomended, and it ran fine for about a few weeks, then it gradually started running rougher. I have no exhaust leaks, but i do have a header with 2.5 inch msa exhaust all the way back. It kinda hisses when you accelerate, sounds like an exhaust leak, but its not leaking, and it seems to come from inside the MAF. It also run smooth then gets rougher as it warms up. ill also mention that i plugged the egr. so it was a little on the lean side, so i richened it up a bit. It also started backfiring a bit, i thought it was because it was rich, but i leaned it out and it still back fires, the back fire occures every time i let off the throttle, it just starts popping bad. Does it sound like i might have a intake manifold leak and jsut needs retorqueing? or are there other underlying problem that arise when pluging the egr? anyway, thanks guys. Quote Link to comment Share on other sites More sharing options...
woldson Posted November 13, 2008 Share Posted November 13, 2008 I take it you have the o2 hooked up? I have never had a issue with the egr being blocked off. Check very throughly for a intake leak, (kinda tough), then re torque. Also read up on the efi bible, if you have not already. Quote Link to comment Share on other sites More sharing options...
silver280zx Posted November 13, 2008 Author Share Posted November 13, 2008 Ive heard about the efi bible but what is it? No i dont have any oxygen sensors, its a january 79 model. The only emissions stuff it had stock were the carbon canister and the egr. thanks for the input Quote Link to comment Share on other sites More sharing options...
(goldfish) Posted November 13, 2008 Share Posted November 13, 2008 I believe this is what they mean, found here... http://atlanticz.ca/zclub/techtips/EFI&fuel.htm Quote Link to comment Share on other sites More sharing options...
jasper Posted November 13, 2008 Share Posted November 13, 2008 Popping back on a decel is normaly caused by an exhaust leak close to the head, lean mixture ,or air injection that ocurrs on decel. (possible diverter valve/air injection issues) Quote Link to comment Share on other sites More sharing options...
silver280zx Posted November 13, 2008 Author Share Posted November 13, 2008 ok thanks guys, i retorqued thegasket, and it still runs a bit lean, but itdoesnt really backfire anymore. I did a little reading in the efi bible, and it sounds to me like the mixture spring might be wound too tightly, but im not sure i want to go in and tamper with it. Is there a way to get fuel mixture readings on the car if it has no oxygen sensor on it? I have a port for one, because the header came with it, but the car didnt come with one stock. again thanks for the help. Quote Link to comment Share on other sites More sharing options...
woldson Posted November 14, 2008 Share Posted November 14, 2008 Mark the afm so you can put it back to stock position and have a little fun! Before that, clean the chts! Not only the connectors, but the probe as well. Quote Link to comment Share on other sites More sharing options...
silver280zx Posted November 14, 2008 Author Share Posted November 14, 2008 ok will do, can the temp sensor in the 79 model affect the mixture at all? Quote Link to comment Share on other sites More sharing options...
woldson Posted November 14, 2008 Share Posted November 14, 2008 Ok so I looked up the fsm on your year. No o2 sensor. The sensor that helps control mixure is the water temp sensor. The thermadine switch controls cold start injector. So when you engine is cold you are in a enriched state. When that cycle is over the extra fuel is shut down and you are running on just your injectors. At that point the fuel enrichment is driven by the wts amoung other divices. Quote Link to comment Share on other sites More sharing options...
silver280zx Posted November 14, 2008 Author Share Posted November 14, 2008 Ok so I looked up the fsm on your year.No o2 sensor. The sensor that helps control mixure is the water temp sensor. The thermadine switch controls cold start injector. So when you engine is cold you are in a enriched state. When that cycle is over the extra fuel is shut down and you are running on just your injectors. At that point the fuel enrichment is driven by the wts amoung other divices. Ya i had had problems in the past with the wts, and replaced it, but it seemed to flood the motor before, i think i may replace it again, its cheap and couldnt hurt. Quote Link to comment Share on other sites More sharing options...
S130Z Posted November 14, 2008 Share Posted November 14, 2008 Did you use the exhaust/intake gasket that came with the header? Did you have problems after or before installing the header? Quote Link to comment Share on other sites More sharing options...
silver280zx Posted November 14, 2008 Author Share Posted November 14, 2008 Did you use the exhaust/intake gasket that came with the header? Did you have problems after or before installing the header? I used the gasket that came with it. The problem occured randomly, nothing to do with the header, the header heas been on for years, i just changed the gasket out because my old stock steel one leaked. I think its a mixture problem or an ignition timing problem. Does anyone have a good timing setup they like for a stock 79 car with IHE and a stock motor? Quote Link to comment Share on other sites More sharing options...
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