1988 5.0 Swapped Conquest wont idle on its own

Munind · Jun 17, 2018

Greetings everyone! I here recently ran into an issue with my Conquest where it wont idle on its own. Any information to help narrow the cause would be a great help.

The car will start up just fine but will not idle on its own. If i give it some throttle it will hold and stay on no problem.
I thought it would be a loose throttle cable so i tightened it up just a hair and it would stay on no problem.
Then when i got to take it for a little drive around the block it runs real funky.
Its feels as if it does not want to go when trying to take off in first or anywhere in the higher rpm range.
I can roll off in second but i would pretty much have to short shift as the car would sort of buck or hesitate real hard.
Im thinking it could be something fuel related as when im cruising it at a steady pace, i can feel the car just slightly bucking.
Its not bucking violently or anything at this point but just enough to where you can feel it. more like a slight nudge.

Anything helps! Cheers

Stock 302 from an 88 Foxbody
Only has cams and has been converted to mass air flow.

General karthief · Jun 17, 2018

Check out the 'surging idle checklist' in the technical/how to section of the fox tech forum, it covers everything that needs to be done to keep you from wasting time and money.

jrichker · Jun 17, 2018

You guys with idle/stall problems could save a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first two posts have all the fixes, and steps through the how to find and fix your idle problems without spending a lot of time and money. It includes how to dump the computer codes quickly and simply as one of the first steps. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix.

It's free, I don't get anything for the use of it except knowing I helped a fellow Mustang enthusiast with his car. At last check, it had more than 250,000 hits, which indicates it does help fix idle problems quickly and inexpensively.

Steel1 · Jun 17, 2018

Is it a stock ecu ?
If so can you pull codes ?

Munind · Jun 18, 2018

Steel1 said:
Is it a stock ecu ?
If so can you pull codes ?

Yes stock ecu but im gonna try to get a scanner.

jrichker · Jun 19, 2018

Munind said:
Yes stock ecu but im gonna try to get a scanner.

Dumping the codes is a good idea, but you don't need a scanner to do it. All you need is a paper clip or jumper wire. SEE the Surging Idle Checklist I posted, it has the how to dump codes as one of the first steps.

2000xp8 · Jun 22, 2018

Conquest, as in dodge conquest?
I had a white Mitsubishi starion flareside turbo as my first car, loved that thing (engine was a total pos, but I still loved it).
Got any pictures?

Bucking is rarely a fuel delivery issue.
IMO, it's ignition related and from my experience it's the wires or distributer.

Munind · Jun 25, 2018

2000xp8 said:
Conquest, as in dodge conquest?
I had a white Mitsubishi starion flareside turbo as my first car, loved that thing (engine was a total pos, but I still loved it).
Got any pictures?

Bucking is rarely a fuel delivery issue.
IMO, it's ignition related and from my experience it's the wires or distributer.

I don’t have any engine bay pictures but this is all I got right now.

A buddy of mine suggested that as well. I haven’t had the time to but I’ll try to pull some codes here soon. Hopefully we can get it back on the road soon.

2000xp8 · Jun 25, 2018

Nice, I had the identical car but in white.
The factory turbo engine was one of the biggest POS's ever made, it was a rarity that someone eclipsed 100,000 miles.
Mine had major blow by under boost and eventually a cracked head and blown head gasket.
Sold it to a friend who replaced the engine then soon after fell asleep at the wheel and rolled it, or else I would have tried to buy it back and do a 5.0 swap.
Is it true that just 351 motor mounts and a 5.0 drops right in?

Steel1 · Jun 25, 2018

Yeah those cars bring back some memories, I can remember wanting one back in the mid to late 80s.
I saw one for auction at Barrett Jackson N.E. this weekend, not sure what it sold for.

Mustang5L5 · Jun 26, 2018

jrichker said:
Dumping the codes is a good idea, but you don't need a scanner to do it. All you need is a paper clip or jumper wire. SEE the Surging Idle Checklist I posted, it has the how to dump codes as one of the first steps.

Considering it's an engine swap car, the check engine light might not be wired up.

Just easier to spend the $25 on this and always have it in the toolbox

Amazon product ASIN B000EW0KHWView: https://www.amazon.com/INNOVA-3145-Ford-Digital-Reader/dp/B000EW0KHW

jrichker · Jun 26, 2018

Mustang5L5 said:
Considering it's an engine swap car, the check engine light might not be wired up.

Just easier to spend the $25 on this and always have it in the toolbox

Amazon product ASIN B000EW0KHWView: https://www.amazon.com/INNOVA-3145-Ford-Digital-Reader/dp/B000EW0KHW

That truly is a great idea, and It has been at the bottom of the dump codes tech note for several years now.

The paper clip or jumper wire alternative is there for those who on an extreme budget or stuck on the side of the road and need a quick and easy way to do some diagnosis.

goinforbroke2 · Jul 9, 2018

i was having a bad surging idle with my 5.0 swapped e36 recently too where it would only run for a couple of seconds and crap out i went through the checklist (really good info) and ended up finding the base idle all out of wack just an idea

Munind · Jul 24, 2018

2000xp8 said:
Nice, I had the identical car but in white.
The factory turbo engine was one of the biggest POS's ever made, it was a rarity that someone eclipsed 100,000 miles.
Mine had major blow by under boost and eventually a cracked head and blown head gasket.
Sold it to a friend who replaced the engine then soon after fell asleep at the wheel and rolled it, or else I would have tried to buy it back and do a 5.0 swap.
Is it true that just 351 motor mounts and a 5.0 drops right in?

Im honestly not sure as I purchased the car with the swap already completed but I’ll tell you, the motor looks right at home!

Munind · Jul 24, 2018

Mustang5L5 said:
Considering it's an engine swap car, the check engine light might not be wired up.

Just easier to spend the $25 on this and always have it in the toolbox

Amazon product ASIN B000EW0KHWView: https://www.amazon.com/INNOVA-3145-Ford-Digital-Reader/dp/B000EW0KHW

I did end up purchasing this scanner however when I followed the proper procedure to pull codes I got nothing.

Munind · Jul 24, 2018

To update everyone, it ended up being the MAF sensor! I had called a mustang enthusiast that suggested a few things with the MAF sensor being the first and thankfully the last. Fortunate enough, my buddy had a spare sensor to let me borrow to test and it ended up being it! Thanks to everyone for the interest and input.

1988 5.0 Swapped Conquest wont idle on its own

Munind

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wonder how much it would cost to ship you a pair

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