Hesitation during acceleration

[97bomexgsx]

Hey guys, I am in need of some serious help. I just bought a 97 gsx eclipse, it has 66725 miles on it. When I rev the engine the does normally, but when im driving down the road it BOGS down and hesitates horribly. It does this no matter what gear I am in, according to the guy the plugs and wires only have 1500 miles on them, the wires look perfectly fine. The gas gauge does not work fully once it hits a 1/4 tank it stops there, the only other issue is when im idling the oil pressure gauge drops all the way down and the oil light comes on, but as soon as I touch the gas at all the light goes out and the gauge goes back to normal, even when the gauge is down there is no tapping or anything from the engine. I just can not seem to figure out why it bogs down and hesitates so bad oh an it happens after 4k RPMS under 4k it seems fine, it also seems like it only happens when i floor it, if I slow accelerate I dont think the hesitation or bog is there. I did put some injector cleaner in it Friday and it didn't seem to make any difference at all. Can the oil pressure issue cause this? I think the oil pressure is maybe just the gauge malfunctioning. Im pretty sure the guy did not really drive the car, it seems like it prob just sat in his garage 90% of the time. I the only things I could think of is maybe the plugs, injectors, or I read something about the crank positioning sensor causing the same issues. It also sometimes but not all the time idles a little rough, as well as sometimes when im driving and press the clutch in to stop the rpms drop very low like to 0 and it acts like its going to die but then the rpms go back to 1k. I have had 1 instance where she didn't want to start for me and about an hour later it started fine. Please help me in any way you can she has so much more power then I can get out of her and its driving me crazy. As far as MODS go under the hood all I know of is,

18g Mitsubishi Turbo, ported and clipped
34mm flapper installed in turbo
Ported exhaust manifold
Ported O2 housing
Full 3” Turbo back Apexi N-1 exhaust system
Injen CAI
HKS SSQ BOV
Turbo XS MBC
GReddy upper and lower intercooler piping
Apexi Turbo Timer


It is currently running at 12lbs of boost, thank you in advance for any help-ideas.

 

[92AWDHX40]

Do a boost leak test.

 

[casuprock]

Boost leak check. If you're haven't already, install a wideband.
Knock sensor malfunction- maybe you're retarding timing a lot if the sensor thinks it's knocking
Clean the MAF with MAF cleaner

The oil pressure sending unit might be malfunctioning or the wire has a lose connection if you get wonky pressure readings. Fix connection or replace the sending unit and see if that goes away.

Our stock gas gages are terrible, this is a common problem. You can pull the sending unit and clean the slider off with some deoxidizing electronics contact cleaner, that may help.

Get a spark tester and make sure your coils are giving good spark.

12psi on an 18G?

 

[97bomexgsx]

Thanks for the replies, ill have the boost tested and see what happens, also ya the guy I bought it from has the boost set to 12psi, and it has the 18 mitsi turbo, Should I change this?

 

[97ebaygst]

Not to sound like an ass but do u know what a boost leak test is? I ask because of your comment "I'll get the boost tested" your not testing boost but rather if there are any leaks in the piping that is being boosted.

 

[97bomexgsx]

Yea I know what a boost leak test is, I do not have the equipment to do so. Im hoping one of the shops around here does. But yes I do understand what it is and how it works, thanks for checking though.

Meant to put this in the last post, but I am not sure if the 12psi is too little or too much for the 16 mitsi turbo, any suggestions on that? Also is there any way to check for boost leak without a boost leak gauge and the connector to the turbo, that's the only what I know of to do it.

I also meant to mention in my original post that the A/F gauge bounces from lean to rich constantly until I accelerate and when I accelerate aggressively it stays on rich until I let off, I asked the guy I bought it from if it was accurate and he said he installed it and wasn't sure, if it is working I assume it shouldn't be bouncing like that or on rich when hitting the gas? Please correct me if I am wrong, I am fairly new to the turbo stuff, I under prob most of it like how it works and what not but as far as exactly what it should be tuned, adjusted I have no idea.

 

[Nasty Dream]

it also seems like it only happens when i floor it, if I slow accelerate I dont think the hesitation or bog is there.

when you floor it, you get turbo boost. When you accelerate casually, it's mostly all engine. Therefore the bog-down issue is something to do with the turbo or its counterparts. Not the engine (although it's possible). I think something is hooked up wrong or leaking regarding the hoses.

I'm a newbie myself, but have you double checked to make sure the BOV is hooked up right? You might get bogging from that if it's installed wrong.

A/F gauge bounces from lean to rich constantly until I accelerate and when I accelerate aggressively it stays on rich until I let off, I asked the guy I bought it from if it was accurate and he said he installed it and wasn't sure,

Maybe do some searching on how to hook up the A/F gauge too. I don't actually have one of these yet, so I can't be much help here.

He may have hooked some things up wrong. Sounds like he didn't have the best information when he hooked that stuff up. But don't change anything until you are sure. Don't experiment, in other words.

 

[Calan]

12psi is low boost (really low in fact) for almost any bolt-on turbo upgrade. BUT, you need to get your car in working order before researching on how to turn it up or how far. Also, I don't see any fuel upgrades in your mod list, so you will be limited in how much you could turn up the boost anyway.

Do the boost leak test as mentioned, as well as checking for exhaust leaks. Also make sure all the maintenance has been done (belts, fluids, filters, plugs, wires, etc).

Your "A/F" gauge is useless; it's nothing more than a light show triggered off your narrowband O2 sensor. For proper tuning, you need a wideband sensor and gauge.

Once the maintenance is done, you really need to invest in some logging and tuning software. You can't do much of anything without it.

 

[97ebaygst]

What kinda a/f gauge is it? Narrow or wideband? Narrow bands are pretty pointless although I guess It's a good thing it reads rich. So I guess it does help a little. Also if it is narrow band, when your car is at idle it is continuously adjusting the fuel air mix so its normal to see it bounce up and down, its not really that noticeable on a wideband.

 

[Calan]

I guess It's a good thing it reads rich. So I guess it does help a little.

If anything, that can cause a false sense of security. An AFR of 12.5:1 is rich on a NB display that is switching around stoich... but I sure as hell wouldn't tune a car on pump gas to that AFR at WOT, even if it really was exactly 12.5:1...which it probably wouldn't be in the first place.

 

[97ebaygst]

If anything, that can cause a false sense of security. An AFR of 12.5:1 is rich on a NB display that is switching around stoich... but I sure as hell wouldn't tune a car on pump gas to that AFR at WOT, even if it really was exactly 12.5:1...which it probably wouldn't be in the first place.

point well made. I didn't know narrow bands sucked that bad

 

[Calan]

point well made. I didn't know narrow bands sucked that bad

Well, they don't.

They work perfectly fine for what they are designed for, which is to output a switching signal centered around a lambda of 1 (14.7:1 AFR for gasoline).

The problem is, people try to use them to measure an actual AFR that is outside of their accuracy range, which is very narrow...hence the name.

 

[97bomexgsx]

Awesome, guys thank you very much! I will have a boost leak test and exhaust leak test done and see what I come up with. IDK if this will help you guys tell me what it may be but, this morning when I went to work it was 56 degrees out instead of the usual 90 to 110 it has been and the car barley hesitated at all in fact in 1st which is usually the worst I didn't notice it at all. Any ideas on that? Also from what Nasty dude said is that right the BOV could cause that? Im not sure how to tell if its hooked up correctly or not, I know it works cause I can hear it. I really really appreciate the info on the boost leak and the exhaust leak, first thing in my mind was bad injectors. Do you guys know how bad it would be to repair a boost leak?

Also as far as the A/F gauge goes I have no clue on anything about it other then the brand of the gauge it's self. The belts look good on it and he did say at 60,000 miles he had Mitsi do all the 60k belt replacements and what not, so I think there good. The plug wires look ok to me I havn't taken the plugs out yet to look at them. I did notice that if I am stopped and REV it up I can smell the exhaust/gas very well. Im not sure if its actually fuel I smell or just the exhaust but either im guessing I shouldnt be able to . I figured a car with that lil miles shouldn't have been doing this, least to say I was wrong just hope to god I can get it in perfect working order its so beautiful and if I can't my WIFE may kill me for buying it . Also I did notice the Injen intake filter looks pretty rough it has a small hole in it and is bent a little bit, he right up against some of the intercooler piping. Could that small hole have anything to do with it id say smaller then a penny. Also is the exhaust smell maybe a leak and could it be causing it for sure?

I know im a pain, but once I get this issue fixed I want to over time have this engine brand new and upgraded. As far as fuel goes what should I do in that area and any other thing I should do to this car to make it B/A once its back to normal?

 

[Robbyd]

i had same problem with my gs, not turbo but still doing same thing. it seemed like it had a lag to 4k rpm's. then my fuel pump went out and i replaced that and fuel filter and it went away. then a couple months after it would do the same thing. from what i read the fuel pump filter in teh tank gets clogged up and causes that but im not sure.

 

[hazmat6135]

my buddy had these probs and turned out his head and both manifolds were pretty gummed up. he pulled the head cleaned all the ports and manifolds and put it back togethyer and the bogging went away. his car basically couldnt breathe when it got into high rpms. (but this was all done after numerous boost leak tests to make sure that wasnt the issue first)

 

[Nasty Dream]

according to the guy the plugs and wires only have 1500 miles on them

hesitated

The plug wires look ok to me I havn't taken the plugs out yet to look at them.

if I am stopped and REV it up I can smell the exhaust/gas very well. Im not sure if its actually fuel I smell

When the engine is cool, check the gap on the plugs. These new plugs may have a gap issue (too wide).

Car started acting up (because of the plugs) he didn't know why and sold the car, thinking it was something serious.

Next redo the grounds on the vehicle. Resistance builds in the old ground wires and grounding points over the years. Put bigger (heavier gauge wire) and more ground wires on the car (or just buy a grounding kit), file down corrosion, etc. If the grounding points are bad (probably), you will get better response and more liveliness - especially at low RPM. And no hesitation.

With either or both of these things done, I think your problem will be over.