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having an issue.
once i turn on my car i have to let it warm up alittle -4-5- min or alittle more before I drive it
i get low idle
engine shaking
and once it warms
It all stops and the car sounds normal
if I don't do this the car starts to throw explosions while running until it gets a good temperature
Check engine light on I'm assuming.
when was the last time you did a tune up?
You be amazed at what a new set of plugs, caps, rotor and wires will do for cold starts.
Also, use ONLY the factory motorcraft plugs.
Sounds like a defective ect (engine coolant temp) sensor. Disconnect its harness and place multimeter leads across both terminals to test ohms. The fuel mixture is richened during cold start and warmup mode,but when the ect goes bad,it triggers the ecm to back off on fuel delivery, which is opposite of what you want during cold starts.Its screwed into the metal heater pipe assembly on the passenger side of the lower intake.
Check for a vacuum leak too.It causes the o2 sensors to read lean,which triggers the ecm to "falsely" richen the fuel mixture. That overrich mixture triggers the raw gas odors you smell.
Last edited by wbrockstar; 05-29-2018 at 07:20 AM.
Oops sorry man.I must have completely looked past the part of your post where you stated you had replaced the temp sensor already.It was the ect sensor you replaced, right?? Not the temp sender for the water temp gauge?? If you did replace the ect sensor & you bought a generic brand at Autozone,it wouldn't hurt to test it anyway.Generic brand sensors are hit or miss.Its more rare for one to go out,but the iat (intake air temp) sensor also has a large influence on the fuel mixture during cold start & warmup mode too.
I assume your smog system components are likely deleted too,since you removed the egr system components,but if Im wrong and they're still in place,do a quick check for vacuum leaks at the two vacuum hoses that run between the tab/tad (bypass/diverter) solenoids and tab/tad valves.Both of those solenoids are energized during cold starts/warmup mode,which triggers them to supply vacuum to the tab/tad valves.Once the engine warms up,vacuum is still supplied to the tab valve,but its cutoff to the tad valve.So if the problem occurs when the engine is cold & in warmup mode (i.e.- vacuum is present to both valves) but the problem disappears as soon as the engine has reached operating temp (i.e.- vacuum is present to the tab valve but its cutoff to the tad valve) the vacuum hose to the tad valve is most likely to blame.
Another check: When you start the engine to let it warm up,remove the vacuum hose from the fuel pressure regulator and check inside the hose to make sure its not wet from fuel and doesn't have an odor of fuel.Verify fuel isnt seeping out at the regulator port too.Fuel present at either location means the fpr is leaking.
If the items above pass,run KOEO/KOER tests.To do this,let the engine run until it reaches operating temp then shut it off.Make sure the ac is off,the transmission is in Park (auto) Neutral (5 speed) & the clutch pedal is down (if 5 speed) Get a jumper wire and insert it between the single wire STI terminal and the Signal Return terminal at the self test connector,turn the key on/engine off and start counting the cel (check engine light) flashes.86-93 Mustangs will flash the codes out in two digit format.Write them down then run a KOER test and post your results.If you don't know where the STI and SIGRTN terminals are located or how to do these tests,the following link will show/explain everything. List your results in a future post and we'll help you trouble shoot them.
The ecm controls idle,using the iac valve, and the valve is opened & closed depending on the ect reading.If coolant temp is cold,iac voltage is low.If coolant temp rises,iac voltage will increase,which closes the valve.So voltage to the iac valve increases as the engine goes from cold to hot and the valve closes as the engine goes from cold to hot.Therefore,if the ect is sending out an inaccurate reading, it will also affect iac function.
The following link details the strategies
used for each running mode,so you can see which components function/dont function during certain modes.
The ecm controls idle,using the iac valve, and the valve is opened & closed depending on the ect reading.If coolant temp is cold,iac voltage is low.If coolant temp rises,iac voltage will increase,which closes the valve.So voltage to the iac valve increases as the engine goes from cold to hot and the valve closes as the engine goes from cold to hot.Therefore,if the ect is sending out an inaccurate reading, it will also affect iac function.
ECT does 2 main chores: tells ECM (PCM nowadays) to enrich fuel mixture when cold starting, thus it's partly an electronic "choke". Second, it tells PCM when engine has reached sufficient temperature to allow "closed-loop" operation of the O2 sensors. Those "hone" the mixture then depending on load, speed, etc. imp
05-28-2018, 02:32 PM
1993 mustang 5.0 EFI
