car keeps dying at idle???

[mustangGT85]

hey guys, i have a question i'm sure someone here can help me with. i just swapped the 87 5.0 and AOD into my rx-7, and it ran. ran nicely. i've only had the car running for about 15 seconds at a time(either the belt kept getting thrown off, which i fixed, or the leak in the upper radiator hose, which i also fixed, or just running it for a few seconds so one of my buddies can hear it over the phone).

but now, my car will start, but it keeps dying. it will stay on in neutral if i work the gas pedel, but if i let off, it ussually dies in a couple of seconds. also dies if i try and put it in gear. i figured it might be out of gas, since the none of the gauges are working, i wasnt sure. so i went and got about 3 gallons of gas and put it in, and the same thing. it starts but keeps dying. my father in law, thinks that maybe since the car has been sitting for such a long time, there might be bad gas, and it might be messing with my injectors. he told me to drain all the gas, put fresh gas in, and put in fuel injector cleaner in. i was thinking of using that seafoam stuff. i heard it works great. i'm going to try this, but i would like any suggestions you guys have as to what might be causing this.

thanks guys,
~Steve

 

[The Shape]

Man I don't have any suggestions off the top of my head, but I would love to see pictures.

 

[mustangGT85]

no problem








here are some. i have a bagillion pictures of my swap. lol


~Steve

 

[The Shape]

Looks good man!

 

[jstang209]

manifold looks nice!

 

[jrichker]

Will the engine run if you press the throttle sightly? If not, check the fuel pressure while the engine is running. Use the schrader valve located behind the alternator to tap the fuel line for a pressure check.

If the engine will run steady above 1000 RPM, you have an idle air adjustment problem. See the sticky "Help me create the Surging Idle Checklist" at the top of the forum for help with your idle problems.

 

[srothfuss]

Also might be a good idea to check your timing, might be too retarded... It might be close enough for your car to run above 1000 RPM and then die below.

 

[mustangGT85]

yeah i think that is what it is. that and bad gas. iput in half a coffee cup of atf, and that seemed to help out a little bit. it idles on it own now. but the idle seems really low. not sure what the RPM is cuz the tach doesnt work yet. thanks jrichker.

the shape and jstang: thanks. i really liked how well the manifold came out too.

 

[HISSIN50]

Another vote behind JRichker.

Is it SD or MAF? I assume SD, and if so, having the IAC working properly is more critical for proper idling (vs MAF).

Neat project and Good luck.

 

[mustangGT85]

yeah speed density.

 

[HISSIN50]

From what I have read, SD differs from MAF in that it should have its idle set with the IAC connected (vs MAF, which does not require the IAC to be connected). SO this makes having the IAC function properly even more important.

(Joe, if you know of different info or have a differing opinion, please correct me. This was per a friend with a factory SD manual - I dont have one to confirm this).

 

[mustangGT85]

ok ok, so i'm going to check my timing make sure its ok. should i just set it to 14degrees if it isnt there already? also what about cleaning my IAC with carb cleaner? and how should i "set my idle" with that little screw with the spring under my TB?

~Steve

 

[HISSIN50]

ok ok, so i'm going to check my timing make sure its ok. should i just set it to 14degrees if it isnt there already? also what about cleaning my IAC with carb cleaner? and how should i "set my idle" with that little screw with the spring under my TB?

~Steve

Steve, here is a write up which covers the basics. Some guys like soaking the IAC in WD-40 and scrubbing it, some use carb cleaner, some both, etc.

The write-up should give you a good general idea, sans the part about setting it with the IAC connected. Absent confirmation on that, I would perhaps try setting the idle without the IAC connected (per the article) and see how it does. That is nice because if your IAC starts to get dirty again, you will see a diminished cold-idle and idle compensation for A/C, etc, but it should continue to have a normal hot-idle.
But if it idles like poo this way, I would reset the idle with the IAC cleaned and connected (per how I think SD idle should be set).

Others very well might have a differing opinion on all that (this is just what makes sense to me).

Timing at 14* should be fine. If in doubt, set it at 10* (stock) and you can dial up the advance down the road.

Good luck.

 

[mustangGT85]

ok guys i got some new info. my Map sensor wasnt connected and its broke. my father in law said he heard a crack when reinstalling the intake but couldnt see anything. kinda funny how he didnt tell me that until i dug out the map sensor. lol all well. a couple of questions:
1. What vaccum hose plugs to the map sensor? where does the other end go?
2. does anyone have a good diagram of how the hoses under the intake manifold hook up. i just want to make sure they are hooked up right on my car. cuz one hose is plugged off. my father in law is a good mechanic, but he is more of a carb 350 kinda guy.

hissin50: thanks for that writeup. i saved that page when i was checking out "surging idle page". and i really appreciate your help thus far. actually i really appreciate everyone's help.

~Steve

 

[mustangGT85]

also, doe anyone have a vaccum hose diagram perhaps for the 87 5.0 AOD. cuz i heard that if any of the hoses are disconnected or not plugged or in the wrong location, then the whole system messes up. is this true?


~Steve

 

[jrichker]

also, doe anyone have a vaccum hose diagram perhaps for the 87 5.0 AOD. cuz i heard that if any of the hoses are disconnected or not plugged or in the wrong location, then the whole system messes up. is this true?
~Steve

You should be able to source vacuum from almost any port under the manifold for any vacuum requirements.

The system isn't like a carb where you have one port off the carb to supply the vacuum advance for the distributor and another one for the PVC.

 

[HISSIN50]

Steve, Here are a couple of Tom Moss's diagrams (site host is S+2B's).

Vac diagram One

And vac pic two

These should get you going in the right ball park. A stockish motor should have ~ 18-20" hg of manifold vac at idle (SD is sensitive to the vacuum signal so it is important).

Good luck.

 

[HISSIN50]

Oh yeah, those are based on an 88 SD motor, which should be VERY similar, if not identical, to your 87 SD motor.

 

[mustangGT85]

thank you guys


~Steve

 

[mustangGT85]

hey guys i have a quick question and comment. just now i went to start my car, and i wasnt really thinking, and i started my car with out the map sensor hooked up. it started and i held my foot on the gas ever so slightly to keep it idling at around 1000 rpms. well i slowly took my foot off the gas, and it stayed idling at prolly around 800 RPMS or so.(this is all by ear). but it idled like how it should. no fluttering, didnt kill itself(shut it self off). my question, is it bad to run the car(for now) with out the map sensor connected? becuase by my logic and thinking, when the map sensor was plugged in, it was telling the computer, either wrong info(because there was no vaccum line hooked up) or bad info(possibly broken map sensor).

hissin5.0 and jrichker, i would love to hear your opinions and facts on this. thanks guys

~Steve