ZCar Forum banner

Status
Not open for further replies.
1 - 3 of 3 Posts

·
Registered
Joined
·
51 Posts
Discussion Starter #1
Okay here's the story. '87 n/a 5 spd. I dropped in an '86 turbo engine with 80K miles on it, and I'm using the stock n/a 5 spd. I kept my stock 87 na engine harness, intake manifold w/ all accessories, afm, and 02 sensor. The car will start and run with the 02 sensor plugged or unplugged, so I just have it unplugged for now. I have 2 turbo computers I've been using, one is an '84 and the other is an '87, both auto. With either computer the car will start and run and drive. The car will not idle on it's own (jumps around between 4 and 600 rpm then dies after 5-10 seconds), but will stay running if I keep a little pressure on the pedal. When it's below 1000 rpm it runs pretty rough, but when I rev the motor it's very smooth like it should be. When I'm using the '84 computer, the idle will smooth out and sound much nicer if I unplug the chts. With the '87 computer it runs rough with the chts plugged or unplugged, makes no difference. Another observation between the computers is this: when you turn the ignition to "on" and the fuel pump primes, it never shuts off with the '87 computer, but shuts off after a few seconds as it should with the 84 computer. I don't know if this matters.

Aside from the rough idle, the car feels slow. I've driven it about 5 miles close to home and it doesn't feel any faster than my n/a. It builds boost like it should and the gauge shows a steady 6psi boost at wot. Also gauge shows 18in vacume at idle. It accelerates smoothly, doesn't stumble or anything, but it just isn't quick. Something is keeping my power down and I can't figure out what.

I did a compression test and all cylinders are good. They range from 160-150 psi, which is within spec according to haynes. I'm running ngk plugs set at the gap specified in the manual, and my timing is at 10 deg btdc as per manual. The plugs were brand new when I put them in, and I checked them while doing the compression check. 4 were perfect as they should be, and 2 were a little more black. They all looked okay to me.

I checked the ecu codes, it was throwing 14 (vehicle speed sensor), 23(idle switch circuit), & 24(park/neutral switch). I can't find the idle switch circuit in my manual, and no I haven't tried to adjust the idle on the plenum.

Can anyone give me some ideas or point me in the right direction? I'd appreciate any help I can get. Thanks.
 

·
Registered
Joined
·
4,279 Posts
check the connection to the air regulator.

a friend of mine did the swap, he has close to the same problem, but his was a bit more than you said, it turned out to be the gasket that sits under the plenum, it was leaking so check that too.

I want to say you have a vac leak somewhere, I don't know what the vac number should be but mine is over 20 in vacuum at ide, I'll have to look again tomorrow to give you exact number but I know it's over 20.

if your car doesn't seem like it's faster than your NA then you did something wrong for sure.

you can NOT use Auto ECU's for 5 speed, well, you shouldn't!! wether thats is your problem or not I don't know but it **** well might be, get an ECU for a 5 speed before you do anything else.
 

·
Registered
Joined
·
1,991 Posts
What computer do you have in now? You must use same year computers. The 84-86 have a seperate module that controls fuel pump. It is located under the battery tray. you must have that for thae early ECU to work. Buy a Stand-Alone, and quit messing with all those factory harnesses, and problems.
 
1 - 3 of 3 Posts
Status
Not open for further replies.
Top