Guest Darthmentos Posted July 22, 2003 Share Posted July 22, 2003 This is an odd one and I'm out of ideas, can you ford gurus figure this one out? 1987 ford 5.0L stock everything.... stalls when hot. parts replaced/ temp sensor oxygen sensor plugs/wires/cap & rotor coil car has injector pulse, and strong spark. 3 mechanics (one a ford dealership specialist) are left totally clueless. I am thinking catalytic converter. Ideas gentlemen? thanks in advance- darth... Quote Link to comment Share on other sites More sharing options...
Guest Darthmentos Posted July 22, 2003 Share Posted July 22, 2003 oops forgot symtoms... car runs well when cold but stalls out when at operating temp, then refuses to run for about 25 minutes. then it runs fine.Black sooty discharge upon rev up. also replaced dist module with no apparent results/ Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted July 22, 2003 Share Posted July 22, 2003 Sounds like your getting too much fuel, when engines are cold they like a rich mixture, so engine keeps running. When hot, it stalls when too rich. Did you have all the injectors checked out of the motor? Could be one or more is leaking. Quote Link to comment Share on other sites More sharing options...
Guest Darthmentos Posted July 22, 2003 Share Posted July 22, 2003 yup, have already covered the basics on it. Just seems to be a sneaky hard to find gremlin. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted July 23, 2003 Share Posted July 23, 2003 Perhaps the cold start injector is constantly on, instead of turning off when engine warms up. Thus the engine would run fine when cold, but as it warmed up, the A/F mixture would become too rich. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted July 23, 2003 Share Posted July 23, 2003 Perhaps the cold start injector is constantly on, instead of turning off when engine warms up. Thus the engine would run fine when cold, but as it warmed up, the A/F mixture would become too rich. No cold start injector on the Ford 5.0. Quote Link to comment Share on other sites More sharing options...
Guest bluex_v1 Posted July 23, 2003 Share Posted July 23, 2003 How long does it take to get up to operating temp and stall out? is it a matter of a minute, or after driving around for several? Once it gets up to operating temp, does it tend to stall out only if it is under acceleration, cruise, idle, deceleration...or any of the four? If you were to start it up in the morning after sitting cool all night, how long will it sit there at idle before it stalls? Would this be the same amount of time if you repeated the proceedure the next morning in the same weather conditions? Does it even stall if you give it no throttle input after its warmup? Is that 1987 the year of manufacture or the model year, and was it manufactured for sale in Calif? (ie, is it a maf or speed density system?) And no error codes I assume, right? When you say that it refuses to run for about 25 minutes, do you mean it won't start at all or it just runs like crap and then dies? If it runs like crap and then dies, how long does it take before it dies again? Have you started up cold and driven it hot with the o2 sensors disconnected? Does it sound like it has any exhaust leaks? Quote Link to comment Share on other sites More sharing options...
Jwink25 Posted July 23, 2003 Share Posted July 23, 2003 ECU? Quote Link to comment Share on other sites More sharing options...
Mudge Posted July 23, 2003 Share Posted July 23, 2003 Should be around 2 minutes to get those O2 sensor(s) warmed up. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted July 24, 2003 Share Posted July 24, 2003 2mins for O2 sounds slow to me and wouldn't that set a code if the O2s were hosed? If it's an '87 it's Speed density - Cali or not. '88s were MAF in Cali only and all starting in '89 were MAF. Totally stock? SD cannot handle changes as well as MAF but it can handle some changes before you're out of it's adjustment range.... Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted July 24, 2003 Share Posted July 24, 2003 Are there any codes set in the computer? During the warm up period, the car is running "open loop" mode. In "open loop" mode, the computer only looks at throttle position. After warm up, the car goes "closed loop" and votes on O2 sensors, MAP sensor, throttle position, etc... Have you replaced the MAP sensor, and have you got it plugged properly into the manifold. Speed density cars need the MAP sensor as the primary input for determining Air flow and therefore fuel requirements. Good Luck, Dan Quote Link to comment Share on other sites More sharing options...
Guest Darthmentos Posted July 24, 2003 Share Posted July 24, 2003 these are all things I have not thought of. I will have to ask some of the local shops and dealers with my store to find out wheter these items can be tested or if it is a replace only scenario. Good tips guys I'll try some of this stuff and see what happens. Quote Link to comment Share on other sites More sharing options...
Mudge Posted July 24, 2003 Share Posted July 24, 2003 2mins for O2 sounds slow to me and wouldn't that set a code if the O2s were hosed? Depends how hosed they are. If its not that bad, it will simply give the car split BLMs, now if its running 11.5:1 on one side and 14.6:1 on the other, its probably going to run kind of crappy. But if the computer is dumb (being old), and its not that far out of range, then it wont know any better - thats where logging comes in. If the O2s are 30k miles + old on a car of that generation the O2(s) are due for replacement. Nowdays they last 80-100+k miles. Quote Link to comment Share on other sites More sharing options...
Guest bluex_v1 Posted July 24, 2003 Share Posted July 24, 2003 He did say he already replaced the o2 sensors...so I'm thinking bad wiring or bad connectors and a lower than true voltage from the sensors. I would expect the ford mechanic to check the output voltage at the sensor and then also right before the ecu pins and make sure it is around .5, if it is lower than that, it would make the ecu enrich the mixture. What doesn't make sense to me though is if it won't start back up at all for 25 minutes after it stalls. If I remember right, the ecu ought to reset its strategy to where it uses stored fuel tables in open loop mode, bypassing the o2 sensors at start up, then in a matter of seconds probably it should determine it is at operating temp and attempts to go back into closed loop (unless the 87's function radically different from EEC-IV). ..so that's why I wanted to know exactly what 'refuses to run' meant. (unless it is an o2 sensor problem causing the stall, and then a totally seperate issue causing the hot start problem) If it is the o2 sensors he ought to be able to unplug them and run ok enough not to stall out on the default tables right? Bad MAP seems more likely I guess. I may be way off, got no experience, I just started reading Probst Quote Link to comment Share on other sites More sharing options...
Mudge Posted July 24, 2003 Share Posted July 24, 2003 It would be extremely bizzare for the O2 to be responsible for the car not starting, in fact I have never heard of it even when they are completely dead (car will stay in OL) so its not likely. Unplug the battery or ECU/ECM/PCM fuse and see if that makes a change when it doesn't start, I am guessing it wont make a difference. In which case, maybe an injector is dying or something? How do the plugs look? It really really helps to be able to datalog. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted July 25, 2003 Share Posted July 25, 2003 FWIW - my Mustang has only one O2 wired up. It will start and run but a little funky and one bank goes DEAD rich to the point that the catalytic glows The OEM ECU will be replaced with a Mustang unit and AEM W/B Quote Link to comment Share on other sites More sharing options...
cobraz240z Posted November 1, 2003 Share Posted November 1, 2003 check the MAF sesor gasket i had a mustang and it did the same thing and sense i did that it workfine its just a air leak try it thats going to be the problem Quote Link to comment Share on other sites More sharing options...
Guest Darthmentos Posted November 1, 2003 Share Posted November 1, 2003 We found out what was wrong with it. Sort of. We replaced the distributor - and it hasnt done it since then Quote Link to comment Share on other sites More sharing options...
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