1. Fuel cut fremlin(5 secs after WOT, fuel or spark turns off for about 1/4 of a second...then back on...does it systematically every 5 seconds when under WOT/full boost*stock boost*). Swapped out fuel pump and filter with known good ones...still does it. Previously swapped out MAFs, TPS, etc etc...any ideas?

 

2. Coolant dissapearing. No noticable external leaks or signs of leakage...and no smell of coolant. Where else could it be?

 

That is all for now...I hope. :-\

is there a fuel pump relay? id replace that with a known good one.

any computer codes set? id make damn sure all vacuum lines were good.

do a leak test. pressure test the cooling system, dye helps if you learn nothing from the pressure test.

Have you tried swapping out the boost sensor that triggers the fuel cut? Maybe in its old age it has gotten a little trigger happy.

the ECU doesn't sense boost, it senses how much air the MAF sensor is reading.

fuel pump relay is next.

 

no boost sensor on 87+ MAF cars...its the MAF its self. replced with several form cars that DONT do this...and it still does it.

 

vac line are good. no codes set.

the ECU doesn't sense boost, it senses how much air the MAF sensor is reading.

Could you explain in more detail? I mean, in colder climates, the air is much denser so the heater element in a mass air flow sensor (hot wire type) would be harder to heat up, which would increase the voltage signal in the sensor. That would mean fuel cut would/could be experienced at stock boost levels at say -10F temps for example. What is it exactly that determines fuel cut sense some people don't experience it at all? Is it necessary in order to run higher boost, you have to 'heat' up the air prior to the airflow sensor so that the air isn't too dense, so the sensor element doesn't become too hard to heat up? That would explain why some people in warmer/hotter climates wouldn't experience the 'fuel cut' problem but it must be more than this.

 

I had to actually read up on air flow sensor (hot wire maf sensor in particular) to see how they work. The flapper maf is the one that senses volume (like the older turbo'd subes) so it would seem better fit for them to be used to cut fuel if it was totally dependant on volume. Why go to a hot wire maf sensor to measure air volume to cut fuel when the previous sensor would've measured air volume/flow better? This all just seems confusing to me.

how about a compression check for the coolant loss issues.

 

did you try getting it up to operating temperature and then pulling the throttle open while looks under the hood. sometimes very small leaks won't be visible very easily - heat, higher rpm's and wiggling some hoses might help show it's face. or let it idle in the same place for 30 minutes and looking underneath.

 

any coolant out the exhaust?

 

wet floorboard on the passengers side?

i found something interesting. I cant wait to post it and take it off the car.

hey will, do you have the boost controller still hooked up to the compressor side of the turbo? on mie, i have it still wired up but not connected to the turbo, just a hose going from the compressor to the waist gate. no boost cut and it still works properly.

Subyrally you have an 86 which means easy fuel cut eliminator just unplug the boost switch

 

 

Kevin, you are right you can get boost cut on stock boost depended upon how dense/cold the air is. WJM can explain it better :/

Could you explain in more detail? I mean, in colder climates, the air is much denser so the heater element in a mass air flow sensor (hot wire type) would be harder to heat up, which would increase the voltage signal in the sensor. That would mean fuel cut would/could be experienced at stock boost levels at say -10F temps for example. What is it exactly that determines fuel cut sense some people don't experience it at all? Is it necessary in order to run higher boost, you have to 'heat' up the air prior to the airflow sensor so that the air isn't too dense, so the sensor element doesn't become too hard to heat up? That would explain why some people in warmer/hotter climates wouldn't experience the 'fuel cut' problem but it must be more than this.

 

I had to actually read up on air flow sensor (hot wire maf sensor in particular) to see how they work. The flapper maf is the one that senses volume (like the older turbo'd subes) so it would seem better fit for them to be used to cut fuel if it was totally dependant on volume. Why go to a hot wire maf sensor to measure air volume to cut fuel when the previous sensor would've measured air volume/flow better? This all just seems confusing to me.

The hot wire MAF is a mass flow device, I doesn’t measure volume (size), its calibrated to measure the amount (mass) of air flowing through it, air fuel ratios are mass ratios. Because it uses heat transfer into a fluid stream, it compensates for density changes from ambient temp and altitude. And because it measures actual flow (not calculated, like a MAP system), it can also compensate for changes for in volumetric efficacy, from wear or mods. In some ways the hot wire MAF is a superior, the down side is that it does present an inlet restriction, but if properly sized that not a big issue. I think the reason that a lot of factory systems have moved away from them is cost.

The ‘87+ EA-82T ECU does not sense boost level, so the fuel cut is based on flow, the designers picked a flow level just above what the engine can achieve under stock conditions. To much flow = failed waste gate, so it shuts off the fuel. Its conceivable that mods that increase overall flow aside from boost increase like intake, exhaust or cams could bring on a fuel cut.

Hope that helps

Gary

... you can get boost cut on stock boost depended upon how dense/cold the air is... :/

With an ALL STOCK system you shouldn't get ECU induced fuel cut, there may be some other problem. Measuring the voltage output from the MAF would be the only way to know for sure.

 

Gary

For your coolant leak I would check the intake manifold gaskets and the hoses connections for a small leak under pressure. The pros have a chemical they can put in the coolant and use a UV light to look for signs of an external leak. I think there is a small hose near the water pump that is easy to overlook.

For your coolant leak I would check the intake manifold gaskets and the hoses connections for a small leak under pressure. The pros have a chemical they can put in the coolant and use a UV light to look for signs of an external leak. I think there is a small hose near the water pump that is easy to overlook.

In the old days, and I assume still today, the colorant used in green antifreeze is flouroscein:

 

"Sodium fluorescein is added to some commercial antifreeze preparations (ethylene glycol) to a final concentration of approximately 20 micrograms/mL as a colorant to aid in detection of automobile cooling-system leaks."

"Fluorescein dye also is added to radiator fluid to help identify the source of a leak. The fluorescein in the fluid fluoresces when viewed under ultraviolet light."

So, I would think that all you would need is a UV source (blacklight, Wood's Lamp) to check for leaks in a system that uses Green-dyed antifreeze. Given the crowded engine area of an EA82T this wouldn't give me much consolation. Mine always seem to find new and innovative ways to leak, and I have seen the leak trail travel a foot to somewhere viewable. :-\

dude..i think i have the solution for you.

 

 

From what i remember you are running that "greddy" mushroom style air filter.....correct???

 

if so...your problem is this. The air entering the Air Flow meter is too turbulant. The air needs to be nice and straight when it enters the air flow meter, or else the computer will get wonky readings.

 

 

You need some way to straigthen the air flow.

 

What we did. Go to Mc. Donalds, and steal a handfull of drinking straws. Cut the straws into like 1 inch pieces, and make a "honeycombe". Tape them all together, and some how install them infront of the Air Flow meter....I'm not sure how your filter adapter works. but you can usually put them in the filter adapter. Once you have your "honeycombe" and have it packed into the air filter adapter, Go get some Bugscreen for screen doors. Cut a piece and stretch it over the straws and around your entire air filter adapter, so when you put your filter on, it holds the bugscreen in place.

 

 

Should make a difference.

 

A quick way to check...throw the stock airbox back on and see if it does it.

hey will, do you have the boost controller still hooked up to the compressor side of the turbo? on mie, i have it still wired up but not connected to the turbo, just a hose going from the compressor to the waist gate. no boost cut and it still works properly.

 

with mine hooked up it did odd things...like peak boost to 30 psi and back it down to 7...and the other way (hooking it up backwards) would yeild 20+ psi all day long. either way with that thing there or not, it still did odd crap. thats a feature for 87+ turbo cars. the 85-86 only has the hose going from the housing to the actuator.

 

 

as for the cut...under STOCK conditions...aka, when the cars in 100% stock form...it would do this...apply WOT, full boost comes on...count to 5...WHAM! 1/4 of a second ignition or fuel cuts off. does it stock and modded. does it with 11 psi as well. I can run 11~12 psi all day long. Over that, it DOES NOT do the 5 second thing, and count to 10...THEN the real overboost fuel cut happens...turns fuel off until boost decreeps to ~6...then everything turns back on. Sometimes it cuts after 5...most of the time, 10 seconds after 13+ psi.

 

as for coolant leak...hmmmmmmm........

From what i remember you are running that "greddy" mushroom style air filter.....correct???

 

A quick way to check...throw the stock airbox back on and see if it does it.

 

Yep, im running that filter.

 

As i just posted at the same time you posted that...it did this when I had the car at absolute 100% stock form...and it still does it.

 

Ive got something to try that I found in the parts catalog today...I will post up pics and results....

the straws idea sounds interesting...I'll try that just for the fun of it. That should add some TQ.

dude..i think i have the solution for you.

 

 

From what i remember you are running that "greddy" mushroom style air filter.....correct???

 

if so...your problem is this. The air entering the Air Flow meter is too turbulant. The air needs to be nice and straight when it enters the air flow meter, or else the computer will get wonky readings.

 

 

You need some way to straigthen the air flow.

 

What we did. Go to Mc. Donalds, and steal a handfull of drinking straws. Cut the straws into like 1 inch pieces, and make a "honeycombe". Tape them all together, and some how install them infront of the Air Flow meter....I'm not sure how your filter adapter works. but you can usually put them in the filter adapter. Once you have your "honeycombe" and have it packed into the air filter adapter, Go get some Bugscreen for screen doors. Cut a piece and stretch it over the straws and around your entire air filter adapter, so when you put your filter on, it holds the bugscreen in place.

 

 

Should make a difference.

 

A quick way to check...throw the stock airbox back on and see if it does it.

 

I am going to pack my extra filter adapter, and go get a TON of straws today. I think this just might work...along with maybe getting some TQ out of it.

make sure they don't come apart, that might make the turbo un-happy

make sure they don't come apart, that might make the turbo un-happy

 

 

The MAF has screens on both sides of it.