93 Sc400_easy Start But Won't Idle

[jaycin]

Bought this 93 in 95 with 13000 miles on it. Put only 14000 more on it in the last 14 years. You might say I don't use it very much. My old ford P/U gets all the miles. This past week I decided to take it for a ride. It started right up but died as soon as I released the gas peddle. Stomped the peddle and it idled OK. AT the stop sign (quarter mile or so) it died again. Would not idle but started each time (about 5 restarts). So I held the peddle down in NEUTRAL at 1000 RPM until the engine warmed. Then it held the idle and I had no more problem that day. But the problem resurfaced the next day. I would appreciate some feedback as to what the problem might be. Many thanks .

[jamesbondsc300]

Bought this 93 in 95 with 13000 miles on it. Put only 14000 more on it in the last 14 years. You might say I don't use it very much. My old ford P/U gets all the miles. This past week I decided to take it for a ride. It started right up but died as soon as I released the gas peddle. Stomped the peddle and it idled OK. AT the stop sign (quarter mile or so) it died again. Would not idle but started each time (about 5 restarts). So I held the peddle down in NEUTRAL at 1000 RPM until the engine warmed. Then it held the idle and I had no more problem that day. But the problem resurfaced the next day. I would appreciate some feedback as to what the problem might be. Many thanks .

a few quick questions....

how often would you say you drive it? Once a week? Month? Are you using 91 or better octane fuel? If it is sitting for extended periods of time moisture can build up in the fuel tank. First I would try "SEAFOAM"(only use SEAFOAM). You can pick this up at any autoparts store.It works very well.Don't buy the other crap, its just plain alcohol. Run whatever bad gas is left in the tank out, then pour in the SEAFOAM and fill the tank with 91 octane...93 if you can get it like we have here in Mississippi. If this doesn't solve your problem after 2 tanks(2 cans of SEAFOAM) then change your fuel filter. It's located just in front of you rear driverside tire.WARNING!!!!(this is a !Removed! to do!) Be prepared for this to take at least 45mins-2 hours. Everytime I do one on these cars it seems like the fittings are frozen! Wear Eye protection! fuel+your eyeball=bad day:) Hope this helps! Good luck;)

[jaycin]

Thanks for your reply. The gas cannot be the culprit. I drive this car about 6 times a year and each time I refill the tank. The last trip took the full tank to refill (October) and it's always 93 octane. The real question might be --- After the car gets to full warm-up, why does the problem dissappear? If the gas had excess moisture, the problem would persist long after start-up. Could the problem rest in the trottle linkage in your opinion?

[lexdud]

Bought this 93 in 95 with 13000 miles on it. Put only 14000 more on it in the last 14 years. You might say I don't use it very much. My old ford P/U gets all the miles. This past week I decided to take it for a ride. It started right up but died as soon as I released the gas peddle. Stomped the peddle and it idled OK. AT the stop sign (quarter mile or so) it died again. Would not idle but started each time (about 5 restarts). So I held the peddle down in NEUTRAL at 1000 RPM until the engine warmed. Then it held the idle and I had no more problem that day. But the problem resurfaced the next day. I would appreciate some feedback as to what the problem might be. Many thanks .

I have the same problem ...

I have a 93 SC4 with 52000 miles. About 6 months ago the car would suddenly stall if you were driving and took your foot off the gas. Just the other day I started it and it died as soon as I take my foot off the gas. I did the following to diagnose the problem:

1) Removed and cleaned the IACV. My valve was near mint condition and clean. Not the problem.

2) Removed and test the MAF per the shop manual. MAF test OK.

I now go out to my driveway, start the car right up, take my foot off the gas and watch it die immediately.

I wish someone could/would provide an answer ... perhaps this has happened to you. How did you fix it.

Good luck OP ...

[jaycin]

Luxdud, Wouldn't a dirty MAF or IACV give me a Check Engine Light? I get no such indication.

[jamesbondsc300]

Thanks for your reply. The gas cannot be the culprit. I drive this car about 6 times a year and each time I refill the tank. The last trip took the full tank to refill (October) and it's always 93 octane. The real question might be --- After the car gets to full warm-up, why does the problem dissappear? If the gas had excess moisture, the problem would persist long after start-up. Could the problem rest in the trottle linkage in your opinion?

This a shot in the dark....A big maybe if you will. What about the ECU? maybe there is a problem with the "open loop fuel" mapping. This could rxplain the problem going away when it is warmed up. After your car warms up it goes into "closed loop mode"(starts using signals from the oxygen sensors). Its possible that the ECU is somehow malfunctioning and running way too rich in open loop mode. I'm not sure about the throttle linkage. whats the car idling at on a cold start? whats it at when its warmed up? Pull out one of your plugs...is it black? (this signals a wayyy rich condition) This problem has got me stumped so far, but don't give up. I'll do some studying and get back with you.

[eatingupblacktop]

Welcome to the club jaycin!

I think 007 is onto a possibility with the ecu and cold start system.

Staying with this thought, I'm thinking the cold start injector might be on too long and flooding the engine. This could be as a result of a malfunctioning injector switch or timer in the ecu.

Another possibility is your injectors may have become somewhat restricted when cold, causing a lean out condition during warmup and thus your idling probs during the open loop phase. Once warmed up, they operate normally.

You could also have similar symptoms with an overly rich condition where the injectors have developed a poor spray pattern and aren't atomzing the fuel correctly, causing the fuel not to burn properly.

Pulling a plug as 007 suggests could reveal if this condition might be present. You could also pull an injector and bench flow test it.

[jaycin]

Those are some good suggestions. Tell me how to bench test an injector please. I think the first thing I'll do is clean the injectors. What type of cleaning or brand would you suggest I use to add to the fuel tank? Is there an optimal level of fuel in the tank to get the most out of the additive? I appreciate your time.

[jamesbondsc300]

Those are some good suggestions. Tell me how to bench test an injector please. I think the first thing I'll do is clean the injectors. What type of cleaning or brand would you suggest I use to add to the fuel tank? Is there an optimal level of fuel in the tank to get the most out of the additive? I appreciate your time.

all you need is one of these......don't got one of those? Thats ok ;) , just try LUCAS Fuel injector cleaner first(they actually make products that somewhat work). Just follow the instructions on the bottle. in most cases if your having bad spray patterns from a fuel injector chances are its beyond cleaning(in other words replacement or rebuild time baby)but first have them bench tested to make sure your not just changing parts and guessing. The problem with cleaning a fuel injector is "varnishing". Fuel is great at cleaning stuff off except for varnish deposits. Chemicals do exsist that clean off varnish, but they would also ruin your injector and fuel line seals :cries: To be honest most Injector cleaning products are junk(they will swear up and down that they clean varnish and deposits, but they lie) Besides, everyone knows you can fix your blown head gasket with some great stuff in a bottle from your local parts store for only $9.99 right? hahaha! . The LUCAS will help a little(sometimes)Just give it a try...it might fix your problem

[eatingupblacktop]

To answer your question, some swear you can't fix a faulty injector or get any sort of performance change from an injector service. Others swear the opposite. Personally I think you can condition the injectors to prevent them from failing, but as 007 mentions, if they're seriously blocked or rusted, replacement is the only cure. In Canada, premium fuel doesn't contain ethanol. Top tier premium also contains detergent additives which eliminates the need for using injector cleaners.

A lot of members here have used seafoam. Do a search and read up to decide for yourself if it's something you want to do. Amsoil makes a cleaner. So does Redline, Chevron Techron and others. How effective they are you will have to research for yourself again. Careful with the old "miracle in a bottle". Often it's more like "Trouble in a bottle"!

An injector prob could be as simple as some bad rubber o-rings which are cheap. Injectors, however, are expensive to replace. As for testing, if you had a scope you could check the duty cycle. There are also fuel injector testers that blink when the injector cycles. Parts shops might have them. Don't know how well they work though. Believe it or not you can take a long screwdriver and hold it up against the injector. You can actually feel it pulsating or vibrating as it opens and closes. If you put your ear up to the end of the screwdriver you can also hear it. You can also do this to listen to your valves (old mechanic's trick).

You can get your injectors tested for less than $8 ea at a good shop, don't know how much your dealer would charge. You could also get your injectors ultrasonically cleaned, balanced/blueprinted so that all of your injectors are flowing at the same rate with new pintle caps, o-rings and filter baskets at about ~$16/injector. That's a lot cheaper than new injectors. Again, evaluate whether your injectors need this service or would benefit from it before spending your money. Here's a link to one shop that does this service:

http://witchhunter.com/. Not sure of their prices.

[jamesbondsc300]

To answer your question, some swear you can't fix a faulty injector or get any sort of performance change from an injector service. Others swear the opposite. Personally I think you can condition the injectors to prevent them from failing, but as 007 mentions, if they're seriously blocked or rusted, replacement is the only cure. In Canada, premium fuel doesn't contain ethanol. Top tier premium also contains detergent additives which eliminates the need for using injector cleaners.

A lot of members here have used seafoam. Do a search and read up to decide for yourself if it's something you want to do. Amsoil makes a cleaner. So does Redline, Chevron Techron and others. How effective they are you will have to research for yourself again. Careful with the old "miracle in a bottle". Often it's more like "Trouble in a bottle"!

An injector prob could be as simple as some bad rubber o-rings which are cheap. Injectors, however, are expensive to replace. As for testing, if you had a scope you could check the duty cycle. There are also fuel injector testers that blink when the injector cycles. Parts shops might have them. Don't know how well they work though. Believe it or not you can take a long screwdriver and hold it up against the injector. You can actually feel it pulsating or vibrating as it opens and closes. If you put your ear up to the end of the screwdriver you can also hear it. You can also do this to listen to your valves (old mechanic's trick).

You can get your injectors tested for less than $8 ea at a good shop, don't know how much your dealer would charge. You could also get your injectors ultrasonically cleaned, balanced/blueprinted so that all of your injectors are flowing at the same rate with new pintle caps, o-rings and filter baskets at about ~$16/injector. That's a lot cheaper than new injectors. Again, evaluate whether your injectors need this service or would benefit from it before spending your money. Here's a link to one shop that does this service:

http://witchhunter.com/. Not sure of their prices.

Just remembered this(as i was reading blacktop's post about the cold star injector)....I had an old 77 datsun with F/I and the cold start injector was staying on instead of running for a few seconds after start up and then shutting off. I unplugged it to trouble shoot to see if that was the problem(low and behold it worked!). Try it out you have nothing to lose :)