S13 ka24de sputters/looses all power after abt 1/2 throttle?

[v30magna]

I've been tinkering on my s13 off and on for a few months now. I got it to work on as a project in my spare time. Bought it from a recycler and saved it from the crusher. When I got it it didn't run. Through troubleshooting, I found the car had a bad fuel pump, 2 bad injectors, a bad ecu, a bad temp sensor, and a bad maf. I have also replaced plugs and wires, fuel filter, and installed an adjustable fpr with gauge, using the Isis fitting at the rail. Compression is all between 165 and 175, and the vacuum is steady. Pair and charcoal evap systems were removed and all lines blocked to simplify the engine bay during troubleshooting. The tp sensor has been tested and appears to be operating properly. Car is currently auto trans, but I have a mtx swap that I want to install when I get the bugs worked out of everything else.

So what happens is: car starts up fine. Idles properly. Comes to temp, and will even rev properly when the pedal is pushed (while the car is sitting in park). When you get it on the road, driving it, it seems to do fine, until you get somewhere past half throttle. At that point it sputters and seems to loose all power. I've had the car up to 70 mph, but darn thing just looses all power after abt half throttle. Sometimes after the sputter while accelerating, it will develop a very rough idle after I decelerate and it will even die at idle. After sitting off for a while and restarted, the idle will be normal again.

What should I check? It's a very confusing problem.

[v30magna]

Ok. Guess no one had any ideas...

I messed with it today. I checked the spark plugs to see what color they were. I was previously having issues with too much fuel pressure and rich condition (hence the adjustable fpr) This go around they were all proper color, but the gap looked off. They had all opened up to abt .050. I gapped them to .044. Went for a test drive. Seems the issue is mostly solved. It still breaks up and looses power at higher speed and nearly full throttle, but is good otherwise. I guess I'll try checking the timing again and install a new hotter coil and igniter too.

[heychris]

I'd agree with recheck ing your time...especially the advance mechanism

Ch



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[johara2320]

Did you check the cap, rotor and distributor? I had a similar issue a few years ago and did Cap, rotor, plugs, wires, fuel filter and ignition coil. Turns out it was the Distributor itself. If possible, borrow one from a friend or find one at a junk yard with a return policy as they're pretty pricey.

[v30magna]

Ok. Problem is still persisting. Lowering the plug gap seemed to have helped a little, but it still stutters and seems to loose all power if I give it a lot of throttle, and then it has a slight miss when I let back off the accelerator. The miss will continue for a little while, and the car will have a rough idle, sometimes die. But if I just drive it normal and easy for a little while it will straiten right out again. I had it to 85 mph tonite, just taking it easy and rolling on the throttle carefully after a stutter/power loss episode. The car does just fine if I just drive it normally and don't goose the throttle.

Oh, and I replaced the cap and rotor when I did the fuel filter, plugs, and wires a few months ago.

[v30magna]

Ok. I'll try to figure out something with the timing, disty, and I'm gonna re-check my fuel filter. No friends with 240s though. There's only 2 other 240s around here and I don't know the owners.

[johara2320]

Good way to make friends haha. I'm pretty interested in this though so please keep us posted.

[v30magna]

I don't think the other owners are enthusiasts. The s13 belongs to an old lady, the s14 belongs to a kid who works at Walmart. I've spoke to him before at Walmart, but he just thought of his car as an a-b daily, he's not really a car guy.

[v30magna]

I've been busy this week. So I haven't done anymore troubleshooting...

[ultimateirving]

Could be a maf issue/ vac leak possible?

[teachmezuo]

I'm pretty interested in this though so please keep us posted.

[v30magna]

Ok. I will. Getting a nice set of s14 seats in the am. I drove it yesterday. Had it up to 90mph without a single stutter., but I eased up to it. I probably could have gone faster, but I ran out of runway.

[sean.arnold9012]

just had this problem with my car. it sounds like a fuel pressure problem make sure you are getting proper fuel pressure.
my car did the exact same thing. since putting a load on the car and driving requires more fuel more air blah blah blah,
check the pressure

[v30magna]

Been working on other issues.

I did check the fuel filter today. It's still cleaning the fuel, but the fuel on the tank side is really dirty. I had to clean out the tank when I did the pump, and then I put some chemtool in with the gas to clean everything else. I'm guessing since the car sat before I got it, the lines were dirty too. I'm gonna get another new fuel filter and drain the tank and fill it with some fresh 93 octane and give it a try. I'll keep you guys posted...

[v30magna]

Drained the old gas, changed the filter. Filled up with 93. No change. I'll be back when I got more.

[v30magna]

My current "to check" list is: clean maf again, clean throttle body again, check for vac leak again, try running without gas cap to test gas cap, try increasing fuel pressure, diagnose weak or intermittent spark issue. I also suspect fuel pressure issue. I read somewhere that fuel pressure is 34psi until a solenoid is activated at wot, which bypasses vacuum and increases fuel pressure to 44psi. My adjustable fpr is set to 34psi under vacuum. When I remove the vac line, pressure jumps to 38psi. Anyone know of if this might be an issue?

[v30magna]

We'll I cleaned the maf, tried running without gas cap, cleaned cap and rotor. Cleaning the cap and rotor seemed to help a little. I also increased fuel pressure to 37 psi. I test drove after each thing. After increasing pressure and cleaning the cap/ rotor, the issue disappeared for a few minutes. Then the car began to bog at wot, so I stopped and checked the fuel pressure. Pressure had dropped and was fluttering so I upped the pressure. I drove it some more and it was doing ok at wot for a while but then it began loosing power and sputtered. I checked pressure. Once again pressure was fluttering and had dropped. I'm basically seeing that after a little hard driving, or after a few minutes of driving, the pressure drops and flutters, even after adjusting the regulator for higher pressure. I guess I need to try another fpr, and check the fuel pump, sending unit, and fuel lines.

[prominentalex]

As someone previously mentioned... I'm suspicious of the distributor and rotor. My rotor on my Eagle Talon had a hairline crack on it and it describes the exact problem you have. It only really affected it when it was wet, but it sounds identical to your issues. Maybe a faulty distributor/rotor?

[v30magna]

We'll I looked at the disty, looked fine. Rotor and cap look fine. The weather is 80 degrees, sunny. The fuel pressure however is fluttering and dropping after a few minutes of spirited driving. I had not noticed it before because I always checked the pressure before I went for a drive , not during or after...

Even if the disty is bad, I have to fix the fuel issue anyway, so I mind as well do it first. If the fuel pressure were constant and holding i would be looking at the disty first..,

[Kingtal0n]

you do a tune up.
a compression test.
a boost leak test (fill with air pressure to find leaks)
you clean the maf
check the timing as per FSM

profit

[v30magna]

Yes to all except boost leak test. Right now I have a miss throughout the driving range (most pronounced at idle, it sometimes causes the car to stop running.) at wot the car doesn't sputter and loose all thrust as it was doing, but it does feel very restricted at wot, with diminished power. you can tell it is missing at wot.

[prominentalex]

Sounds dumb but maybe the fuel strainer is clogged?

[v30magna]

It is possible. I need to get in there and check it. Gotta go look at a little Toyota pickup tomorrow. I'll keep you guys in the loop. Thx so far.

[v30magna]

Well I spent a few weeks getting my yota like I wanted it. Then I got back to my s13.

Since I had a few weeks use of a friends shop, I went ahead and did the mtx swap, installed my Tien s on kyb gr2, did the five lug swap, and installed some strut tower braces. I did nothing whatsoever to address the stutter issue, however it now seems to be gone. I don't know why. I did notice that The trans mount on the auto was torn badly. So for now I'm gonna assume the stutter was related to the auto trans in some way. If the stutter comes back, I'll let you know...