My car has been a battle ever since i found it, dead in some guys lawn- his "project car" that he hadnt laid a finger on in more than 5 years. I put a jspec engine in it, took off emissions, ported the wastegate, and did a few other little things just to get it going. I've been driving it off and on for the past few months and there are some things i cant seem to figure out.

1. The biggest problem is the biggest mystery to me. Once the car reaches full operating temp, it starts to flood so horribly that the engine will barely run- at least it seems to be flooding, judging by the smell of raw fuel and the fact that when i turn OFF the fuel pump, it starts to run normally for a few seconds. A while ago, i found that unplugging the BAC and plugging it back in would fix this problem and the idle would return to normal, but last time it happened, everything i tried that usually works failed.

My thoughts: This car is an 87, which comes with low impedence injectors and a resistor solenoid to raise the impedence. When i got the car, it had an s5 wiring harness in it, with s4 injectors- so NO RESISTORS. Is it possible that the ECU could have been damaged by being hooked up to the injectors without resistors?
Any other ideas?

2. Just a simple question: could a slight leak under the plastic thing the coolant cap goes on prevent the coolant system from creating enough vacuum to suck the coolant back in from the reservior as the car cools?

 

how does it run if you unplugged the BAC and left it unplugged?

and yes a leak in the plastic cap mount can keep the coolant from returning to the engine on cool down

 

Yeah, thats the strange thing i forgot to mention- i've cleaned my BAC twice, after swapping a different one, that didnt change it so i know my BAC isnt just sticking. I wired in a switch for the BAC thinking that if it happened again, it is alot easier to hit a switch than to jump out of my car at a stop light to unplug the BAC. The switch worked for a while, but then i couldnt get it to return to normal after a while. SO... I tried running the car with the BAC disconected, which seemed to work for a while(other than the part where it wont idle cold), but then it did the EXACT same thing.

So, with or without the BAC it screws up now.

Could a messed up coolant temp sensor do this?

 

Where are the resistor packs at? Arent they in the metal box under the air box?

If this is only at idle, did you check the variable resistor by the map sensor? Try adjusting it.

 

An S5 wiring harness will not plug into an S4 ECU and an S5 ECU will not plug into an S4 drivers side harness. Either this was a chopped up harness or the car had never been run with the harness installed. Are you sure it wasn't an 88 harness?

 

how does it run if you unplugged the BAC and left it unplugged?



Are you new?

 

the ECU has nothing to do with high or low impd. it is all in the resistor pack. also not all 87 were low impd. they carll it 87.5 they switched to high.

and run with the bac unplugged, what are you guys talking about? it will run with it unplugged, it just doesnt like to idle until it warmed up some what. some people take it off when they do emissions removal, i.e. me.

 

I've checked- mine is pre-87.5 and it has low impedance injectors, so maybe it is just a later s4 harness.

The problem isnt just at idle, it completely disables the car... It wont even rev above 1.5k and even after unplugging the BAC, it will not return to normal.

As i said before, this happens once the car is hot WITH OR WITHOUT the BAC hooked up, so i know its much bigger than just BAC problems.

Anybody have any ideas?

WOW. Half of you didnt even read the whole initial post.

 

Are you sure the motor is running good compression ? Do you have hot start problems ?

Hot start problems are usually a sign of low compression.

 

so it will flood while its running? or flood out once its been shut off? if its off then you have leaky injectors.

 

what series JSPEC engine did you put in, and what ecu (part number) are you using?

could the coolant temp sender or air temp sender be bad? Not the one under the oil filter that just feeds the gauge, the one on the back of the water pump housing that feeds the coolant temp signal to the engine, or alternativey the air temp sender.

What I am envisioning is as the car is warming up the sender works fine, but at some temp it goes to infinite resistance or no resistance (not sure how likley this falure mode is), making the ecu think the water or (air) is ice cold, enriching the mixture to the max. This is something to possibly check after you have verified the imp of the injectors, and that the correct harness and ecu are present, allong with the resister pack.

The AFM could also be bad, or ther could be a huge leak between the afm and turbo.

 

Compression is not great, but its okay- definitely not the problem though.

N332 ecu, so s4, s4 block, everything s4 but the wiring harness was wrong.

I have verified that the injectors are early s4 low impedance, and i even tested the entire injector circuit to make sure- the setup had the wrong resistance, but i wired in factory resistors in the factory location. The whole reason i even looked into it in the first place when i put the engine in was because the resistors were IN the engine compartment, but they were just sitting there- NOT HOOKED UP, and there was no place to connect them on the harness.

There is no huge leak anywhere after the afm, i've gone through it several times.

To me, the best idea so far sounds like testing the coolant temp sensor. Thanks for the input, slo. It sounds like that could be the problem- has anybody ever seen something like this happen?

Or has anybody heard of a bad ecu doing this?

 

It floods WHILE its running, but it doesnt kill the engine. It just all of the sudden becomes completely powerless and smells like its dumping a constant flow of unburnt fuel out the exhaust. The idle is VERY rough and it bounces from 250-400rpms.

My car floods sometimes when it is hot (when starting it) due to my low compression, but my injectors were cleaned and tested about three months ago so they arent leaking.

 

Messed up AFM/MAF? If it was reporting too much air.. .the ECU would compensate, right?

Just an idea. but I wouldn't call myself one of the "smart ones".

--Micah

 

GO STANDALONE

lol that will hopefully slove your problems. Or it will help you pinpoint them.

just an idea

 

If your wiring harness is extremely hacked up and ghettofied that could easily be the problem, as well. Going pin by pin and verifily that the correct wire at the ecu plug terminates at the right spot and has a good connection would be extremley tedious. If I were you I would look for a good S4 harness, I beleive the NA ones can easily be modified to run on a T2.

Really any of the sensors with the exception of the O2 sensor (there may be more exceptions) could possibly do this.

I have never owned an S4, so this may be obvious, but can you read the computer error codes. I'm sure its possible. Also especially with early EFI, just because a sensor isn't throwing a code doesn't mean it isn't bad, this is just a place to start.

 

Thanks for the help guys, i'm gonna test my thermo sensor, and if that doesnt work, swap ecu's, and if that doesnt work, i'll find a new harness. My friend's got his torn apart and its the exact same model, so i can use his parts for testing, like the afm and the ecu.

I'd still like to know if anybody's ever heard of an ecu being fried.

 

Ive heard of ecus being fried before plenty of times, not just in rx7s but in all different cars.

This is all just what I think may be possible, I'm not sure if its all true or any is but just a thought.

The ecu can be fried but the car can still run or it may not even start up, this is depending on what is fried and how badly. If the car does run, it will likely have problems and the problems can be different depending upon what part of the ecu is fried.

 

if your coolant temp or thermo sensor were bad it defaults to a warm value, so you may have cold problems but not hot problems

 

only if the ecu recognises that its bad

 

Test your FPR is functioning and fuel is going back into the tank from the return. Also what pump are you running?

 

I'm not anywhere close to one of the smart ones, but have you checked for spark? If you have a coil pack failing that may cause it to flood be cuase it's not burning all the fuel. I'm just guessing here, so don't take what I say to heart, but I would look at the really simple things first.

 

I have a walbro, the fpr could have something to do with it, but i really think this problem is electrical, not mechanical because of how nicely it runs before it screws up.

 

I didnt see anyone say anything about maybe an injector being stuck open? Not sure if it can be the case as it does it only when warm... only thing that popped into my head that I didnt already see listed. Otherwise I dunno

 

I've heard of an older pontiac grand prix with a similar problem to mine, except when it got warm it just died completely.